Hello! Yes, weather = storms = rain, but usually storms. Rain on its own is not enough to cause major bumps, just some bumps in the clouds. I think the sunnier days in general can be attributed to the jet stream blowing all the clouds away, but that's not scientific or anything, just a theory of mine. I've had some terrific flights in a snow storm, in fact one of my happiest memories is taking off when it was snowing with the wing lights on, it looked like a scene out of star wars with the snowflakes streaming past the aircraft like stars.
And then came the landing...smooth but the runway was covered in snow and they had to do some serious thrust reversing and they actually had a compressor stall when they were trying to slow the airplane down, and then the drive home was terrible. But still a happy memory nevertheless