I've used the buses here and I can say with some authority that the service is fair but the buses themselves are crap, big aluminum boxes crammed with people that you wouldn't want to share an apartment building with much less an overloaded bus being driven by someone with less personality than the average disgruntled postal worker...
I think you can safely assume that I don't care much for taking the bus, I'd rather move under my power just to spite the weather.
I've ridden in all sorts of weather and never had any health issues, if I take the bus I can guarantee I'll spend most of the following week getting over something that makes my sinuses whistle and my chest feel like it's full of mud.