How long does the Storm Sorcerer's Storm Guide feature stop rain from falling near you?

Question

The Storm Sorcerer gains the Storm Guide feature at 6th level (XGtE, p. 52; emphasis added):

At 6th level, you gain the ability to subtly control the weather around you.

If it is raining, you can use an action to cause the rain to stop falling in a 20-foot-radius sphere centered on you. You can end this effect as a bonus action.

If it is windy, you can use a bonus action each round to choose the direction that the wind blows in a 100-foot-radius sphere centered on you. The wind blows in that direction until the end of your next turn. This feature doesn't alter the speed of the wind.

The ability to change the direction of wind near you has a specified duration, but for the ability to stop rain falling near you, the feature only says you can end the effect as a bonus action; it doesn't say how long that benefit lasts if you don't choose to end it.

How long does Storm Guide stop rain from falling near you?

I imagine it would be of great use for a party while traveling/camping, but it would be really helpful to know how long it lasts after using an action to start it.

I have been able to find a lot of discussion about the mechanics of the Storm Guide feature (such as whether or not it works against snow or if it works against magically-created wind/rain), but nothing about how long stopping the rain lasts or if it requires concentration (or being awake, such as when the party is taking a long rest).

Answer 1

Forever, as written

The ability as written doesn't have a defined duration, only an end condition - that being that you can use a bonus action to end it. It's not a concentration-based effect, so you don't have to maintain concentration on the ability to keep it going - so you can cast concentration spells, take damage, and even sleep, without the effect ending. There are no other general rules that specify that such effects end automatically after some amount of time, so it will last until you deliberately turn it off.

Notably, this feature's description never calls it out as magical, so it doesn't even qualify as the kind of magical effect that could be dispelled by dispel magic or disabled by an antimagic field, according to the litmus test given by Sage Advice.

If I were adjudicating, I might personally rule that the effect also ends automatically once the rain that triggered it does, just so it's not something that has to be kept track of constantly - though not being rained on is an effect of very little mechanical significance.

Answer 2

Until you use a bonus action to end it.

This class feature is written like a perpetual umbrella:

If it is raining, you can use an action to cause the rain to stop falling in a 20-foot-radius sphere centered on you. You can end this effect as a bonus action.

That’s it. That’s all there is to it. It doesn’t mention concentration or even being conscious. It only ends when you end it because that is the only end condition written into the feature.

But as always...

The DM can rule otherwise.

It seems it wouldn’t be too much of a stretch to rule that you at least have to be conscious for the ability to work, but to be clear, this would be a DM ruling, not rules-as-written.