Dry is good, drought is bad. Need relatively dry and warmer nights so that the chicks do not die of hypothermia. Only so many can squeeze under momma.
As the chicks start to grow, they need insect protein to build weight and grow ... they have just 12 - 16 weeks to grow up. Moisture is key for bug hatches.
Occasional rain is good, prolong cool rain (when you see that wrap around ... rain, cool temps, and north winds that lasts for days and days) that is what drops the brood count down rather quick.
If a hen looses 'em all she renests and often keeps trying into July if not early August. We all have seen those birds in October that can barely fly and all say those have no chance for winter survival.