My little one does not like the rain either, but she does go out in it to potty. Sometimes she ends up going on the porch because she doesnt want to walk through the wet grass
If the weather is too bad, as we live in northern Japan and gets lots of snow, I put pee pads under our awning and she goes there with no problem. I stand at the door and wait for her and she does her business and runs right back to the door whether its raining or not..lol