Why does the rain hurt my face when I ride through it on a bike?

[My Answer Is Best.]

This happened to me yesterday on the Williamsburg Bridge, speed was 25-30 mph. It almost felt like being pelted with small pebbles or rubber bands.
Wasn't hailing* I slowed down to exit the bridge, and I'm pretty sure it was just normal rain. I had to ride slowly though because the rain decreased my braking effectiveness by at least 75%.

 

[I wun some Cooookies.]

It could've been hailing. Most likely because of the speed you were going at.