The weather sealing on the M240-series cameras seems optimistic at best. I've used an M240 in the rain and it made me nervous. I think anything more than a light drizzle and I'd not do it again (water was visible under the bottom plate, with no obvious way to make sure that doesn't happen w/o adding my own sealing).
For heavy rain I think you will just always be better brining something designed with the intention of being used in that sort of weather. A mainline dSLR outdoor camera from Nikon or Canon is usually what I go with.