when it rains here, both hubs and i always ride anyway. our commutes are about 20-25 min on way for me 35 min one way for him (5 and 6.5 miles respectively) so they are short enough that we'll just go anyway and we have showers at work and at home and indoor bike storage at both locations. we have ridden in 10-20 F and rain.
i also ride if there are strong winds.
but if there are 30 mph winds gusting to 50, plus heavy rain (or even really slick roads), i will sit it out in the AM. however if it's the PM, i will just ride home really slowly and take the long route on all the protected lanes b/c i want to ride the next day and taking the bike on the train at rush hour isn't really an option.