Thank you so much!Arizona has a monsoon season that lasts a few months. Desert tarantulas much prefer a dry environment. But providing the substrate is only a little too moist, they come to no harm, as it dries out.
Do you have any spare substrate? If so dry a handful out in the sun, or even in the oven on a baking tray & just sprinkle it on the top of the moister substrate. If not take a small amount of substrate out of the enclosure & dry that. Dry substrate will absorb moisture & help to reduce the overall feeling for your T.
Edited to add. It always pays to keep the area around the water bowl a little moist, by letting the bowl overflow as you top it up. Then next time move the water bowl & do it again. Each time allowing the area moistened to completely dry out. This gives some humidity for your T & gives them a more natural environment. And keeping the water bowl moving around every week or two, stops the substrate from getting mouldy.