What have you been riding fenderless in? There have been a few rain storms where I wouldn't have even tried going out without my fenders. Depending on conditions, you could end up covered in snow without them. My nokians tend to pick up more stuff than my old tires, it's nicer hearing it rattle through the fenders than hit me

If you read this, they talk about when you should and shouldn't need fenders

http://www.icebike.org/Equipment/fenders.htm