Passing along a little info, and of course always open to comment.
Typically when we get a storm, it drives my pH up. I'm used to it, and actually welcome it most the time since I don't have any aeration going on in my pool. Last night we got hammered with a very long storm, around 3 or 4 hours. Checked the pool today, of course the chlorine was a little low, but still in range, lots of leaves and organics in the pool (a ton of carpenter ants for some reason?) but pH was LOW. I did not expect it to be low! My borates were a little low so added Borax, and have a couple of homemade aerators running (wait until you see these things!!!).
Again, just really surprised it shifted pH the way it did, and open to comment!