No, your hub should be ok if you use good quality bearing grease a lot of it.
Yes, lots of rain here too. This whole week was forecast for rain. It's raining really hard as I write this. Damn global warming is messing with the weather.
Anyways, The only parts that seem to me to be affected by rain are my chain, brake cables (and brake pads as they make my entire rear rim black and dirty). The water down here seems to have a lot of minerals in it, like limestone. It seems to deposit in my chain and bike lock also over the course of a school year. I don't know. Maybe it's just me.
For my older dirt jumping ride, The unsealed bearings and cup on my BB got corroded and replaced with a sealed Am. BB, and unsealed bearings on the wheels I had, one of which got destroyed and replaced with a sealed f/f hub. I can't be sure if that was caused by the rain or by my riding style, though, as I rode flat on it before I got my Tantra.
I still do not ride my flat ride in the rain ever just to be safe. I can't justify spending that much money and having it get rusted or wet! Even if it won't really "damage" it. I make sure it never sees the rain. The only exception would be my KHE Geisha freecoaster, which I had on my dirt jumping bike to get to and from classes as I didn't have the money to build a flat ride at that time. The Geisha held up fine to rain, and I only had to grease it a few times. However if you use good bearing grease and a lot of it, you should be fine.