No, rain gets in there, it's really not a big deal.
Matter a fact, STis came factory with a intercooler sprayer.
I wouldn't go off unloading gallons into it when the engines hot though, just due to the fact that in worst case senerio, that cool water on a hot engine could possibly crack something. And something almost has to be red hot for that to happen, just letting you know.
A- it's ok go get water in there in downpoor like amounts.
B- don't spray any metal with gallons of cool water when blazing hot.
2002 blaze WRX- sold:(
2011 Wrx limited
99 Fozz- sold
Eagle eye crew