I LOVE to run in the rain! It only rained once this summer, and when it did, I put on my running shoes and played like a little kid. Sure, my feet were wrinkly and I got a blister, but it was the most fun I've had all summer long.
I don't, however, like to run when it's cool or cold. That's no fun at all.
If you want to run, do it no matter what the weather. If it's hot, cut it short, if it's cold, make it longer- if it rains, just have some fun!!!