Down here in South-central Texas we don't get a lot during the summer.
Last summer was one of the dryer years, so I got curious to see how far I'd have to got if I dug a stock tank.
I want it deep enough that I can put fish in it, too. So early August, late July- dug a trench in the lowest part of Rancho Snakebit. This is basically the bottom of a bowl where everything drains to.
Seven feet down before I got anything that wasn't bone dry, and the clay was as hard as brick mortar.
I stopped about seven feet wen I found sandy clay that was maybe not dry- calling it moist would be a long-shot.
This is the same trench last week before the cold rainy, windy week we had.