I once had a combo guitar amplifier that sat in a room that flooded with water a little bit below center of the cones for several hours. Put it up and blew gentle, unheated air on it for about 4 days until it was dry. They seemed to recover fine and didn't look worse for wear. I was afraid one side would dry and shrink causing issues, but they seemed fine and I never had a problem with them for several more years of use.
If they dry wonky though, you'll be looking at a recone like Wayne said.