Cloudy With A Chance Of Rockets

NASA successfully completed a test launch of their new Ares 1-X rocket today. It's supposed to be the next generation of rocket that will eventually replace the fleet of space shuttles.

The launch was finally completed after several delays that were due to... storms in the area.

This I do not understand. Unless I'm mistaken, rockets are blasted out of the atmosphere, and are designed to withstand the harsh, unforgiving environment of outer space. You know, space, the place with the extreme cold and the hard vacuum and the cosmic rays.

But a rocket can't be launched because it's raining outside?