Biggest wreck in a race I've ever been in was caused by wind... I went to high school in New Hampshire, up around Franconia Notch. Up there, the weather can change on a dime. The night before the race there were 60-70 mph winds through the narrow roads that cut through the notch. Cautionary driving alerts and everything. The next morning was calm, though, so the race went on as scheduled.
Fast forward to about mile 34 of the race. Me and about 20 guys up front have just pulled our winners up a pretty big climb, and we're on a fast descent trying to get up speed for a twisty bit of road with a gradual slope coming up.
The descent ends with a wide left just before the twisties. We're all leaning when all of a sudden this wind comes through the notch, must have been blowing 40-50 mph. Nearly everybody up front went down, followed by guys smacking into us...
This was high school, so of course we're all idiots and running 30-50mm wheels because they look cool... that couldn't have helped matters any...
I think one guy needed stitches in his leg, but that was it... a pretty injury-free albeit spectacular crash...