Storm of Vengeance and Concentration

[ATHATH]

From the description of the 9th level Storm of Vengeance spell:

Round 5-10: Gusts and freezing rain assail the area under the cloud. the area becomes Difficult Terrain and is heavily obscured. Each creature there takes 1d6 cold damage. Ranged weapon attacks in the area are impossible. The wind and rain count as a severe distraction for the purposes of maintaining Concentration on Spells. Finally, gusts of Strong Wind (ranging from 20 to 50 miles per hour) automatically disperse fog, mists, and similar phenomena in the area whether mundane or magical.

I... can't seem to find any rules describing what a "severe distraction for the purposes of maintaining Concentration on Spells" actually DOES. Does the spell force people within its affected area to make a concentration check each round (in addition to the one that they'll be making due to the cold damage)? If so, what's the DC? Does it impose disadvantage on concentration checks made in its area or something? If so, does anyone have a rules (or Sage Advice) citation for that?

[Warder]

It's under Spellcasting -> Concentration:

"The DM might also decide that certain environmental phenomena, such as a wave crashing over you while you're on a storm-tossed ship, require you to succeed on a DC 10 Constitution saving throw to maintain concentration on a spell."

So the DC is 10, but how often do you make the check? Up to the DM. I'd say once per round sounds about right.