It is drizzling. (It is raining slightly.)
It is raining.
It is wet outside.(It is raining.)
It is pouring.(It is raining heavily.)
It is lashing.(It is raining heavily.)
It is raining cats and dogs.(It is raining heavily.)
Rain is not actually dangerous to plane, and you can often fly through rain with no issues at all. The main problem is that heavy rain often impairs visibility.
Although weather accounts for up to a quarter of air accidents worldwide, rain alone has almost never brought an airplane down. One notable exception was Garuda Indonesia flight 421, which suffered a flameout over the island of Java in 2002. Pilots couldn’t restart the engines and had to land the plane in a river, which was successful, though one flight attendant died due to aircraft damage.
Several notable air incidents have occurred due to stalling, which as noted can sometimes happen as a result of frozen rain on an aircraft wing.
