Go ahead and pick one: It's too hot, cold, humid, windy, wet, icy. Weather is a great justification for not running because it shifts all blame to the forces of nature. It's not my fault, you smugly assure yourself. It's that annoying guy on The Weather Channel who predicted the brutal cold front that came through and prevented me from running. Nice excuse. But it's not going to work. The weather is vitally important to all runners, but most runners figure that what doesn't kill them just makes them tougher.