How to handle forest fires? How they start and how they can be ended?

[Jon_Dahl]

My players throw fire-based magic A LOT in the woods. Usually in relatively hot and dry forested areas. I don't how to handle all that. Any suggestions?

If there's any significant fire in the woods, whether instantaneous are not, I give about 5% (it has just rained) to 33% (ideal for forest fires) chance to start a fire. A two-man team that works efficiently to end the fire before it spreads has about a 50% chance of succeeding in 10 minutes, after which the fire gets out of control (although there's still a 60% chance that the fire will simply die out before there's any firecalypse). Any additional person helping the team raises the possibility of ending the fire for about 10%.

[Eisfalken]

My players throw fire-based magic A LOT in the woods. Usually in relatively hot and dry forested areas. I don't how to handle all that. Any suggestions?

If there's any significant fire in the woods, whether instantaneous are not, I give about 5% (it has just rained) to 33% (ideal for forest fires) chance to start a fire. A two-man team that works efficiently to end the fire before it spreads has about a 50% chance of succeeding in 10 minutes, after which the fire gets out of control (although there's still a 60% chance that the fire will simply die out before there's any firecalypse). Any additional person helping the team raises the possibility of ending the fire for about 10%.

Honestly, without modern methods, I doubt it'll be easy to stop a forest fire once started. They would need to expend a LOT of magical effort to create a fire break/lane, bring down enough rain to put it out, etc. Create water is probably one of your best bang-for-the-buck spells here; it's very low-level, scales well with level, but it's a divine spell, so you need clerics and druids busting their hump.

So... don't make it easy on them. Let them start a forest fire and be surrounded by fire, smoke, and hot ash, where they have to flee to save themselves. Set up a scenario in advance where they need to make it to a major break in the forest (river, hills, etc.). Saving throws against smoke inhalation, heat exhaustion, falling debris, etc. Roll randomly to see if they cross paths with some animals or monsters also fleeing the fire; while most will keep running for dear life, pay attention to anything big that may try to run over them to get out of there (Huge size or bigger). The fire may not necessarily burn the whole forest down, either; druids, nature clerics, and a few friendly wizards will most assuredly come to stop it soon as they see it.

If the PCs brazenly brag to anyone about starting such a fire, decide on the nature of their bragging if the local druids, fey, etc. hear about it. If so, don't pull punches. Have some fey who were friends with a dryad that died in the fire look for blood. Have druids track them down to levy quests or curses against them to repay what they've done.

This doesn't have to take over your campaign, but make it a part of it. It'll be a good learning experience, maybe a source of some extra XP (and/or loot) between steps of your campaign, etc.

[ExLibrisMortis]

Friendly Neighbourhood Psion: "Why aren't you using a [cold] energy burst instead?"
Wizard: "Wha...?"
FNP: "Just as effective, but with a fraction of the collateral damage!"
Wizard: "Don't think I can make a coldball, let me check my spellbook..."
FNP: "Spellbook? how quaint I'll just be over there, nice talking to you."

[Bronk]

Well, they started the fire with a spell, so they could stop the fire with another spell (or power).

They could use these spells to put the fires out directly: Create Water (L0, Control Flames (L1), Pyrotechnics (L2), Quench (L3)

They could try calling up water elementals to get things wet or earth elementals to toss sand on things...

They could also try to emulate regular fire fighting techniques by creating firebreaks with fire elementals, or other fire spells like Flaming Sphere...

If the fire is already a full blown forest fire that they can't put out at their level, they might have to do their best to evacuate entire towns.

[J-H]

Control Weather
Downburst (Druid 0 or Druid 1)

If your party keeps setting forest fires, they may run into some angry Treants. Make it an over-CR encounter so they either get cautious or run away.

[tropical_punch]

Just to be clear, you do know that instantaneous fire spells (like fireball) don't set stuff on fire with the rules as they are, right?

[Jon_Dahl]

Just to be clear, you do know that instantaneous fire spells (like fireball) don't set stuff on fire with the rules as they are, right?


The fireball sets fire to combustibles and damages objects in the area.

It's my call that dry wood is combustible enough to be a combustible.

[Jon_Dahl]

Just to be clear, you do know that instantaneous fire spells (like fireball) don't set stuff on fire with the rules as they are, right?

From the Oxford English Dictionary:

A. adj.
Thesaurus »

1. Capable of being burnt or consumed by fire, fit for burning, burnable.

B. n.

Thesaurus »

a. A combustible substance or matter.

I don't care what the rest of the rules say on this matter.

[TheYell]

Yeah in ye olden times which is just about up to the 1960s they couldnt effectively contain a wildfire.

There's enough magical and practical tricks to justify a Profession: Firefighter who rolls to earn per HOUR.

I can see your party being pursued by a Fire Marshal and his posse and being presented with a fat bill.

[Eldariel]

Well, forest fires are completely natural and end naturally. DMG page 87 actually goes in-depth on them and lists them as a CR6 challenge. Thus ones started by player fire would too end eventually, though they'd of course be very destructive (fire is very efficient vs. many lower magic towns and cities as well). But yeah, to stop one unnaturally would take some higher level magic. Fire needs three things to keep spreading: flammable material, oxygen and heat (generally self-produced by the very effect of the fire itself).

Control Weather is a good one. Whatever the time of the year, there's weather that includes sufficient amounts of water to extinguish the flames. Heavily metamagicked Create Water or anything like Blizzard would work, and summons like water elementals and kinda-sorta control winds/air elementals. Though beware, strong winds in reality only fuel and spread the fires unless they bring sufficient volumes of cool air to stop the reaction, or when it directs the fire in a direction with no fuel (such as the already burnt area). To put it all away for sure, you'd need to get rid of the air away entirely and create a vacuum - though in D&D, Hurricane/Tornado-force winds extinguish all flames by RAW (http://www.d20srd.org/srd/weather.htm#winds), which is not exactly the whole story. The spell Thin Air [Frostburn] should certainly work if again metamagicked to be of relevant scope, but rules are silent on the matter. You could probably create vacuums by moving sucking the air upwards momentarily, but there are few rules for e.g. how Control Winds interacts with the surrounding air. If there's a body of water nearby, Control Water could be used. Call Avalanche [Frostburn] would obviously be exceedingly effective. Spells like Blizzard fall into the same spectrum, but Blizzard actually has sufficient scope that it might do something alone (though it's worth noting that Control Weather covers the area of Caster Level 105 Blizzard naturally still). Control Temperature [Frostburn] is likewise a nice spell from a low level slot, granting the option of lowering temperatures within 20 cubic feet per level from a 3rd level slot.

Removing the fuel could be done with effects like Move Earth/Polymorph Any Object/Earthquake/etc. with repeated castings/sufficient metamagic/sufficient numbers to do it in grand scale. This can at the very least create firelines or barriers if done with sufficient scope. Things like chain Gating can of course trivially produce sufficient volume of spellcasting to get the job done but it's a bit of an overkill. Planar Bubble [Spell Compendium] could be used in any number of ways though you'd probably want it tied to some plane other than the material plane for it to be particularly useful.

[BowStreetRunner]

I've traveled in a party that included someone with a Frost Brand (http://www.d20srd.org/srd/magicItems/magicWeapons.htm#frostBrand). That pretty much resolved the issue for us.

[Toilet Cobra]

It's my call that dry wood is combustible enough to be a combustible.

Is a forest really "dry wood" though? I mean, even if there's fallen trees everywhere, they often retain a lot of water in the wood.

I'm not sure a full-fledged forest fire would result unless there was an accelerant in play. If you're looking for realism, a fireball in the woods would probably start a handful of small fires that could get out of hand if left untended long enough. Your party could probably launch fireballs, complete five more rounds of combat (only 30 seconds) and then stomp out any remaining fires without an issue.

[Jon_Dahl]

Is a forest really "dry wood" though? I mean, even if there's fallen trees everywhere, they often retain a lot of water in the wood.

I'm not sure a full-fledged forest fire would result unless there was an accelerant in play. If you're looking for realism, a fireball in the woods would probably start a handful of small fires that could get out of hand if left untended long enough. Your party could probably launch fireballs, complete five more rounds of combat (only 30 seconds) and then stomp out any remaining fires without an issue.

That's almost what I do. "Long enough" is 10 minutes for me and you have to have at least two people doing something worthwhile to stop the fire before those 10 minutes are up.

[tropical_punch]

Huh. I could have sworn there was some rule about instantaneous fire spells not lasting long enough to light stuff on fire. Ignore me then.

[Jay R]

Don't forget the importance of wind. In a moderate wind, the fire is growing and traveling.

And for inspiration, go watch Bambi before you run the game. Really.

[InvisibleBison]

Huh. I could have sworn there was some rule about instantaneous fire spells not lasting long enough to light stuff on fire. Ignore me then.

As far as I can tell, there is no general rule about whether instantaneous fire spells can set stuff on fire. However, fireball and burning hands both mention that they can, which implies that in general fire spells can't start fires. I don't think that counts as RAW, but it's certainly a reasonable way to adjudicate the issue.

[Bronk]

As far as I can tell, there is no general rule about whether instantaneous fire spells can set stuff on fire. However, fireball and burning hands both mention that they can, which implies that in general fire spells can't start fires. I don't think that counts as RAW, but it's certainly a reasonable way to adjudicate the issue.

The general rule can be found in the SRD, in "The Environment" section, under 'Catching On Fire':


Spells with an instantaneous duration don’t normally set a character on fire, since the heat and flame from these come and go in a flash.

So, they don't normally. But maybe sometimes? And Fireball and Burning Hands definitely.

Also, and this has come up before, the Exploration section of the SRD states that fire damage is halved against objects, then reduced by hardness. Wood has a hardness of 5, so a normal 1d6 fire damage from being set on fire looks like it wouldn't ever actually be consumed. However, further down, in the 'Vulnerability to Certain Attacks' section, it states:


Certain attacks are especially successful against some objects. In such cases, attacks deal double their normal damage and may ignore the object’s hardness.

... which would easily cover wood burning in a fire.

[Psyren]

The general rule can be found in the SRD, in "The Environment" section, under 'Catching On Fire':



So, they don't normally. But maybe sometimes? And Fireball and Burning Hands definitely.

To be clear, that passage mentions characters; it says nothing about trees and forests.

Having said that, living wood isn't what I would normally consider to be "combustible." Furthermore, if the forest is dry, then it probably has much more serious problems (like a drought or blight) even before the introduction of actual fire.

[Bronk]

To be clear, that passage mentions characters; it says nothing about trees and forests.

Having said that, living wood isn't what I would normally consider to be "combustible." Furthermore, if the forest is dry, then it probably has much more serious problems (like a drought or blight) even before the introduction of actual fire.

Here's the passage:


The fireball sets fire to combustibles and damages objects in the area. It can melt metals with low melting points, such as lead, gold, copper, silver, and bronze.


It doesn't mention characters. They could definitely be set on fire though!

[Psyren]

Here's the passage:

I was referring to the other passage you quoted, the Environment one about Catching On Fire - that is characters only.

The fireball passage by contrast refers to "combustibles." But while dead wood could easily be rationalized as combustible, a living tree is a little tougher to justify without some form of accelerant.

[Telok]

Is a forest really "dry wood" though? I mean, even if there's fallen trees everywhere, they often retain a lot of water in the wood.

Pine needles, dry leaves and moss, Southern California. Since RL forest fires start from lightning strikes in dry and hot conditions a flash of heat fourty feet across that melts copper ought to do as well.

Also note that hot and dry conditions are not limited to equatorial climates, the interior forests around Fairbanks, Alaska (http://smoke.arsc.edu/current_fires.html), is know for having consistent annual forest fires started by lightning strikes.

[Bronk]

I was referring to the other passage you quoted, the Environment one about Catching On Fire - that is characters only.

The fireball passage by contrast refers to "combustibles." But while dead wood could easily be rationalized as combustible, a living tree is a little tougher to justify without some form of accelerant.

Oh, true. I guess it would default to the forest fire rules in the DMG then. Those say that forest fires can start because of sparks, lightning, or just because everything's dry.

I think when it comes to trees burning even when that particular tree isn't all dried out, it would be pretty similar to a real forest fire. Trees catch on fire all the time, often because of the brush underneath, and often because their leaves catch on fire from canopy to canopy.


Pine needles, dry leaves and moss, Southern California. Since RL forest fires start from lightning strikes in dry and hot conditions a flash of heat fourty feet across that melts copper ought to do as well.

Also note that hot and dry conditions are not limited to equatorial climates, the interior forests around Fairbanks, Alaska (http://smoke.arsc.edu/current_fires.html), is know for having consistent annual forest fires started by lightning strikes.

In the real world, having a lot of smaller forest fires is often considered beneficial, because it clears out the underbrush, opens up the area for more competition, returns nutrients to the forest floor, and and some trees have seeds in pine cones that only open at a certain flamey temperature.

But, if you prevent all forest fires for a lengthy amount of time, all that underbrush and dead trees build up and the resulting fire is much more intense, causing much more damage to the forest.

Looking back at a DnD world, I think that everyone living in the forest, like the fey (especially dryads), or tree dwelling elves, or even druids (what with their quench spells specifically for putting out forest fires), would be stopping any and all fires they could. I'm envisioning pretty much every DnD forest as a natural disaster waiting to happen...

[Jay R]

Looking back at a DnD world, I think that everyone living in the forest, like the fey (especially dryads), or tree dwelling elves, or even druids (what with their quench spells specifically for putting out forest fires), would be stopping any and all fires they could. I'm envisioning pretty much every DnD forest as a natural disaster waiting to happen...

Only if you assume that druids, elves, dryads, rangers, and other forest dwellers know nothing about living in forests.

If they know enough to clear away brush and deadwood, and cook their food over fires, then the problem is fixed.

[Psyren]

Oh, true. I guess it would default to the forest fire rules in the DMG then. Those say that forest fires can start because of sparks, lightning, or just because everything's dry.

I think when it comes to trees burning even when that particular tree isn't all dried out, it would be pretty similar to a real forest fire. Trees catch on fire all the time, often because of the brush underneath, and often because their leaves catch on fire from canopy to canopy.



In the real world, having a lot of smaller forest fires is often considered beneficial, because it clears out the underbrush, opens up the area for more competition, returns nutrients to the forest floor, and and some trees have seeds in pine cones that only open at a certain flamey temperature.

But, if you prevent all forest fires for a lengthy amount of time, all that underbrush and dead trees build up and the resulting fire is much more intense, causing much more damage to the forest.

Looking back at a DnD world, I think that everyone living in the forest, like the fey (especially dryads), or tree dwelling elves, or even druids (what with their quench spells specifically for putting out forest fires), would be stopping any and all fires they could. I'm envisioning pretty much every DnD forest as a natural disaster waiting to happen...


Pine needles, dry leaves and moss, Southern California. Since RL forest fires start from lightning strikes in dry and hot conditions a flash of heat fourty feet across that melts copper ought to do as well.

Also note that hot and dry conditions are not limited to equatorial climates, the interior forests around Fairbanks, Alaska (http://smoke.arsc.edu/current_fires.html), is know for having consistent annual forest fires started by lightning strikes.

Southern California is undergoing a historic drought though. That is not a normal situation for forests. Fairbanks is also far drier now than it was when whatever forests it has originally popped up.

Without getting political, absent some kind of extraordinary event I don't think D&D has the kind of carbon proliferation or other factors to make forest fires as natural an occurrence as they are in our current world. Certainly not enough to leap out at your players yelling "A-HA! You cast fireball! You hear the screams of dryads for miles around as their flesh melts into a puddle in front of your uncaring boots! You guys are in for it now!

[Honest Tiefling]

In the real world, having a lot of smaller forest fires is often considered beneficial, because it clears out the underbrush, opens up the area for more competition, returns nutrients to the forest floor, and and some trees have seeds in pine cones that only open at a certain flamey temperature.

Beneficial for people, at least, but old growth forests are also crap for resources for people typically. I believe that some tree actually rely on forest fires to proliferate as well.

What species of tree are we talking about here? Some are more fire resistant then others, with thicker bark and the like. And then we have trees like the eucalyptus, which takes the 'fire for the fire god' approach to reproduction.

[Bronk]

Without getting political, absent some kind of extraordinary event I don't think D&D has the kind of carbon proliferation or other factors to make forest fires as natural an occurrence as they are in our current world. Certainly not enough to leap out at your players yelling "A-HA! You cast fireball! You hear the screams of dryads for miles around as their flesh melts into a puddle in front of your uncaring boots! You guys are in for it now!

Well, that's what I'm saying. In this scenario, the fires wouldn't be happening often because everyone's being so careful, cleaning up after themselves, and putting out fires when the occur. Then some uncaring adventurers come in, get freaked out by an owlbear, and boom, fire everywhere.

If the adventurers aren't putting the fires out themselves, maybe they're being trailed by a bunch of increasingly irate nymphs and green elf druids...

Basically, now that I'm thinking about it, the whole scenario sounds pretty fun. I'll try to use it in one of my games.


Beneficial for people, at least, but old growth forests are also crap for resources for people typically

Foresty elves often live up in the trees like wee DnD ewoks and wookies, and dryads are in the trees, oaken defenders are covered in trees, and so on.


I believe that some tree actually rely on forest fires to proliferate as well.

What species of tree are we talking about here? Some are more fire resistant then others, with thicker bark and the like. And then we have trees like the eucalyptus, which takes the 'fire for the fire god' approach to reproduction.

Well, there are a bunch of trees like that. Here's a few:
http://dendro.cnre.vt.edu/forsite/valentine/fire_ecology.htm

[Jon_Dahl]

I really suck at biology and physics, but let me explain you something.

A single spark can ignite a forest fire. Forest fires happen in forests. Forests are made of woods and stuff. Lots of stuff. Forests are combustible. The end. I hope you enjoyed the ride! If you have any further questions, don't hesitate to ask!

[Psyren]

I really suck at biology and physics, but let me explain you something.

A single spark can ignite a forest fire. Forest fires happen in forests. Forests are made of woods and stuff. Lots of stuff. Forests are combustible. The end. I hope you enjoyed the ride! If you have any further questions, don't hesitate to ask!

It sounds like you've made up your mind then. So what's the point of this thread?

[Jon_Dahl]

It sounds like you've made up your mind then. So what's the point of this thread?

I want to know how you guys do it. I could be convinced to make some adjustments to the "formula" that I have in the OP, but I refuse to believe that forests aren't combustible by definition.
How much should be required to start a forest fire with a 50% chance of success? And 100%? How fast they spread? DMG has information how fast they spread once started, but I'm talking about the very very beginning. How hard it's prevent them from becoming full-fledged forest fires? This thread already has discussion about these things and I've noted them well. I just refuse to take note of this "live wood doesn't burn" discussion. I don't know about live wood, but https://www.youtube.com/watch?v=3OyrX11cMkE&feature=youtu.be&t=5s
Alright?

[D.M.Hentchel]

Well the book that has rules for fire spreading is surprising Stormwrack (pg 31), assuming that ships and forests are similairly flamable the rules work nicely and will be transcibed here for your convinience are the important bits.

"Fires can and do destroy ships, but it usually takes more than a single flaming sphere to start an unstoppable fire."
"When exposed to fire make an unmodified d20 roll; the DC is determined as shown below."
"Spells that cause an instantaneous blast of fire usually don’t catch inanimate objects on fire, whereas fire spells that burn for multiple rounds are more likely to start a shipboard fire."

DC 5 Struck by a flaming arrow
DC 8 Struck by alchemist fire or similair
DC 10+spell level Attacked by ongoing fire spell
Save DC Attacked by fire ability

"When a ship catches fire, half of the squares exposed to the attack (minimum 1 square) ignite."
A burning square is on fire, dealing 2d6 points of damage per round to that hullsection and dealing the same damagetoany character who enters the square. Each round that the fire burns, roll d%: 01–10, 1 square of the fire dies out; 11–75, no change; 76–100, the fire spreads to 1 adjacent square (a fire typically spreads to 1 new square for each 4 squares currently burning).

As a full-round action, a character can attempt to extinguish a fire in an adjacent square by beating it out, stomping it, scattering burning materials, dousing the flames with sand or water, or similar efforts. A DC 10 Strength check extinguishes 1 square; a DC 20 check extinguishes 2 squares. A create water spell extinguishes 1 burningsquare per 4 gallonscreated (minimum 1square). Quench extinguishes all burning squares in its area."

Normally fireball isn't supposed to start fires weirdly enough.

[Jay R]

A single spark can ignite a forest fire.

Yes, of course. And a single arrow can slay the most experienced warrior.

But that's not how we will model it in D&D, in either case.

The goal of simulation is to produce a system sufficiently less complex than reality that we can handle it reasonably well.

[MesiDoomstalker]

How I do it? Well, what kind of forest is it? Is is a deciduous forest like those found in most of North America? A tropical or subtropical forest? Is it a wet or dry forest? Does it have wet/dry seasons and if so, which season is it? Does the prominent tree species rely on natural forest fires to spread seeds or not? Is it an old growth or new growth forest? Do Sentient Things tend to the forest and if they do, how do they do so? The Smokey the Bear approach or an educated forester approach? How long ago was the last rainfall?

All this matters in determining the chance of a fire from any random ignition event and the likelihood of it accelerating into a forest fire or a devastating conflagration. If you want a simple answer, then I can't help you.

[Telok]

Southern California is undergoing a historic drought though. That is not a normal situation for forests. Fairbanks is also far drier now than it was when whatever forests it has originally popped up.

I can say from personal experience that this is a normal fire year for Fairbanks, over the past twenty years. A high fire year would see half again or more and at least one of the multi-thousand acre fires.

And yeah, even if a little three acre fire isn't significant on a whole forest scale it's really important to the people right next to it.

[Jon_Dahl]

Yes, of course. And a single arrow can slay the most experienced warrior.

But that's not how we will model it in D&D, in either case.

The goal of simulation is to produce a system sufficiently less complex than reality that we can handle it reasonably well.

That's a reasonable argument.

[Jay R]

Here's my first draft of how I would handle it.

Assuming the d20 mechanic, we should ignore anything with less than 5% chance of starting a fire. So in a wet area, with no dry scrub around, I wouldn't worry about it.

If I think a serious chance of fire from the spell exists, I'd probably ask for a wisdom check to let them figure it out before casting the spell. The check would have the same probability as starting the fire. If you're surrounded by dry brush, and fire is extremely likely, then it should be pretty obvious.

I'd probably give a +4 to elves, druids, rangers, or any forest dweller.

If the spell or attack starts a fire, I need to know how dry the area is, how much tinder and kindling are around, how hard the wind's blowing, and in what direction. I assume that in no wind, a fire will spread in an expanding circle, at a speed based on the dryness. In a wind, that circle is slowly moving, maybe a third to one half the wind speed.

At first it's just trying to catch. The fire is trivial to put out in the first minute or so. Just stepping on a small fire is usually enough. At this stage, any PC facing the right direction should get a spot check.

Only after it really has caught will it be a danger. At that stage, a Listen check or a really easy spot check will notice it.

So the biggest likely result is that the party will be without one member - probably the druid or ranger or elf, for about two rounds (unless the enemy live downwind, in which case they will need to stop it.)

But based on my experience with fireworks and campfires, there might be a small chance of an unnoticed smolder that catches fire an hour or two later. This should probably be ignored under the "less than 5% rule," unless it has a really useful plot-focused purpose, or the PCs are being really over-the-top with their fire-based actions..