If I didn't ride in the rain there would be between 115 and 120 days a year when I couldn't ride; if I add in days on which it is snowing that number jumps up to between 130 to 145 days. Getting the right clothing/gear is the key to keeping comfortable. Consider carrying an outer shell (I prefer windproof and highly water resistant) and a cycling cap to help keep the rain out of your face (in cold weather there is nothing quite as good as a full face neoprene balaclava).