Cute game, and fun to play! I see from the description and your other comments that this is your first ever game? Amazing work!
I do have a couple of suggestions. I think the pickup radius on the water particles could have been a bit larger, and a clearer signal for when the cloud is dropping water and when it isn’t would have been helpful (there seems to be an initial burst of rain but you can put out fires for a little while after that burst, but not forever). I found E to switch phases to be a little bit fiddly, since my index finger is also needed to move right, I would maybe suggest Shift instead, but that’s very much a nitpick.
Overall, great game, and extremely impressive for a first ever game!