Well, um, as somebody who lives in a place where it's more often rainy than not... and the humidity is always high... I don't think it matters.
It would matter if you were painting the outside of your house, of course. But the inside? Notsomuch. Mind you, I wouldn't paint in January because it's too cold to open the windows and let it air out. But I'm sure I've painted when it's raining before.
Just don't paint in the dark - without natural light it's very hard to make sure you're doing a good job.