Depending on which camera, it usually has a 50/50 chance, if you shield the camera under your shirt and the rain is moderate, not storming, the camera might have a chance, but if you are caught in a "hurricane conditions" for a hour, obviously the camera will be ruined.
My advice (proven from my past experience):
1. Take out the battery and put it in a dry pocket
2. Move with your back leaned over slightly so you become the camera's shelter
3. Dry off the camera ASAP, and next time, get a storm jacket