Rain, mist, and fog were actually a big problem for many weapons systems in Viet Nam. Even today, they are problems for many precision strike weapons that rely on optics and lasers to operate, and will likely be a problem for 5G propagation.

Radar is able to see through it, which is part of why the B-52 was so critical in Viet Nam. Mid-wave and Long-wave have more capability in such situations due to lower scatter, but even their reach is limited by the weather.

Funny that such a "simple" thing as rain can have significant military consequences.