The "no attack under rain" sounds interesting considering the extreme body heat of the titans ... but itīs too stupid to be relevant, when you think about it some more. "Signs" anyone?
This isn't even remotely on topic but I'd just like to point out that the aliens' weakness to water is because they aren't aliens, they're demons, and they're vulnerable to blessed/holy water, not just any water. People really, deeply misinterpret "Signs".