This varies widely depending on the issuer of the ATM, at least in my part of the EU (SW Germany).
My banking group has (I guess) >90% of their ATMs indoors; I can only think of ever using 4 or 5 locations that were outdoors (my dataset is probably something like 100 ATMs). But there are also some banks which seem to favour outdoor, or at least have less of a strict "indoor policy".
Especially "generic" ATMs at tourist spots or train stations seem to be outdoors.