Last winter I left the lid on my pellet storage bin open slightly during a heavy rain. Next time I went to cook I noticed about 1" layer of swollen, wet pellets on top. I was going to toss them but figured what the heck. I threw them into the hopper along with a bunch of dry pellets and the grill didn't mind one bit. It had no trouble maintaining the temp I set it to, and did not produce excess smoke or ash. I probably would not do this if I had a grill with a long auger, but the auger on the Memphis is very short and wet pellets and dust don't seem to affect it.