How does rainy weather affect ponds?

Depending on your soil heavy rain may produce runoff, and drain into the pool or raise the water table, which raises the water level in your pond. Dry weather does just the opposite.
Oh, I forgot on the earlier question: Welcome to fluther.

To add to that, most fish feed when pressure drops, so the best time to pond fish is right before a weather event, like rain. I grew up with a LOT of ponds around me so if you can get more specific, I’m happy to help.