In any pro race or the Tour, what happen if say left 3km (or whatever) to finish line, a very heavy storm came pouring down resulted in poor visibility, some road floods, bad road traction, etc. Will the race call off.
Usually not. Not even my local races are called off for anything other than hurricane-like conditions. Occasionally they may make a course change mid race if snow makes conditions unsafe but sometimes that doesn't even happen. I think any change 3k from the finish is unprecedented.