car runs really bad when it rains

What is your question?

I am having a strange problem with my car. Whenever it rains the check engine light comes on & the car barely runs. It sounds like it is barely idleing when I get to a red light and just trying to drive it's moving really jerky. I'm not sure how to describe. my car sat parked all day today in the rain. I didn't drive it anywhere until a few hours after the rain had stop & it was running really bad. It's like....I can't drive this gosh darn car if it's raining out!!! LOL. I need help with it