You don't want to be longboarding when it is raining anyways even on a non-electric longboard. I've done it tons of times myself, but there are the following issues:
* bearings will get dirt in them that will greatly reduce their life
* if you don't have expensive ceramic bearings you'll want to pull out the bearings and make sure to get the water out and get them dry, otherwise they might experience some rusting (even the stainless steel ones).
* Stopping distance is way way longer when its raining.
If you're riding in the the rain you're greatly limited to fewer conditions under which you can ride and any time saved by riding will be offset by the time spent drying, cleaning and maintaining your board.
For the rainy season around here (FL,) I got a cheap set of bearings and put some lithium grease in them to keep the water out. The grease will eventually wear the bearings down but it definitely keeps them from rusting, and they actually get a bit of vibration dampening out of it, which is nice on our gravelly-textured roads.
Stopping distance would be the real problem for an electric board in the rain, though.
* bearings will get dirt in them that will greatly reduce their life * if you don't have expensive ceramic bearings you'll want to pull out the bearings and make sure to get the water out and get them dry, otherwise they might experience some rusting (even the stainless steel ones). * Stopping distance is way way longer when its raining.
If you're riding in the the rain you're greatly limited to fewer conditions under which you can ride and any time saved by riding will be offset by the time spent drying, cleaning and maintaining your board.