Yep, been in heavy rain. On my way to, and back during my trip to LOCSTOC in Wisconsin a few weeks ago I met with very heavy rain. Both times were close to home. Both times other traffic was pulling over to wait. The second time there was a tornado warning a few miles away so I pulled off with some other bikers and waited a while under a gas station canopy. No problems with water in the bags. Just don't over fill them so they bulge or gap or there will be water getting in. I made sure they would close all the way around. I did notice on another ride in rain after the trip that there was just a little water that seeped in the bottom seam. I know that is where it came in since I have a tub liner membrane in the bottom of both bags to keep stuff out of the hinge area and there was a little bit of water under that but not over it. Probably from splash coming off the road. So put a thick plastic or rubber sheet in the bottom to keep stuff from getting pinched in the hinge area and also keep water from getting to stuff from the bottom. Never noticed any wetness before or since though, and I've been looking.