I've heard mixed things about the weather in January in Venice... I'm aware that we could experience some of the flooding, but then I've been told we could have weather in the 30's (F) and blustery/rainy or it could be in the upper 40's (F) and clear with a slight wind.
I have the vacation time for January and love to travel places when they aren't mobbed with tourists but I'm wondering how miserable it might actually be!

If you won't mind everything you just described as being possible, you'll be just fine. I was there over Christmas and you just about nailed my experience.

I was there several years ago 12/27-1/1 and had mostly 40s temps, gray and misty (very atmospheric). Had 1 day of torrential downpour. The day we left the sun was shining for the first time but the waters were rising. There was aqua alta on the day after we left.

Also be aware that some restaurants and shops may close b/w New Years and Carnivale for vacation.

If that's when you want to go, do go but I would consider staying a bit away from San Marco which is where most of the flooding usually happens when it happens. I stayed in Dorsoduro where there are a number of well regarded hotels (Ca Pisani, Pensione Accademia, La Calcina) and I think that would be a good option although there are plenty of other locations.
Btw, Venice

It is dampand gray and romantic -- kind of like foggy London. I loved it.

It is definitely not mobbed with tourists.

If you go before or during Carnival, the city will be dressed up with twinkly lights and outdoor concerts, and people (kids and grownups) will walk the streets wearing halloween costumes. Lots of fun.

I was there around New Year's this year, and it was moderately cold, clear, and sunny. I was actually disappointed that it wasn't foggy and atmospheric -- I'll have to try again.

On the other hand, one time when I was there in April it was rainy, chilly, and miserable the whole time. And the Zattere was flooding, so staying at La Calcina (which I was) wasn't such a safe bet. So there you go.

I don't know when in January you're considering, but there are definitely tourists in Venice over the holiday period. Not like the summer, though.

If I were you, I'd go, go, go.

I saw more morning fog in October than we did in December. I'm just not so crazy about aqua alta since we were staying in the often flooded San Marco area.

How will the same time of year be where you live?

Venice anytime is probably pretty darned good. That said, I wouldn't go at the height of tourist season.

Thanks everyone! I'm in DC so January is usually pretty nippy here as well, sometimes with snow. I think we're going to go for it. Weather isn't enough to make me want to skip Venice!

Great, go! I don't have personal experience but a friend who travels a lot went last year in January and loved it. No crowds, saw everything she wanted to see. It's so much easier to get warm than cold.