Rain is often cited by motorists as a reason for driving, but if you believe many climatologists it is actually driving that causes the rain. The link between carbon, global warming and increased rainfall in our hemisphere is well documented.
It is trite but true that there is no such thing as bad weather, just bad clothing. You can make yourself pretty well immune to rain with a cycling cape for less than a tenner. Not glamorous admittedly, but well ventilated and waterproof. The only snag I found is that they can act like a sail, and as any cyclist will tell you, the wind is always against you.