@hypolite I think it may be that red rain is treated as a corner case and not worth modeling for.
Amber rain happens pretty frequently, everything stays open, people are out and about. Black rains or typhoons don't happen every month, but when they do, most things close, and the rain is heavy enough that whatever you do, streets will be flooded. You're out at your own risk.
Red rain is that in-between state that happens once or twice a year, most things stay open, schools stay open if they already opened, but they close if it happens before the schoolday starts.