Not sure where this rumor got started that you can't cook on a MAK when it is raining. That is 100% false! Here in the wet Northwest, we cook on our MAKs in ALL kinds of weather. The MOST IMPORTANT things to be concerned about is 1) Make sure the grill is plugged into a GROUNDED electrical outlet. 2) That you make sure that the pellets aren't exposed to moisture.
If you are not planning on cooking on your MAK for an extended period of time during the wet weather season, then it is a good idea to empty the pellet hopper AND the auger of any pellets. This will prevent the pellets from absorbing any ambient moisture and decomposing, then drying out and causing an auger jam. And you might was well vacuum out the auger tube it is empty, so that when you re-load your MAK with pellets it starts with a nice clean pellet path.