Stupidly warm and humid? (5)
I believe the answer is:
muggy
'warm and humid?' is the definition.
(I've seen this before)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for muggy that I've seen before include "Warm and humid" , "Damp and stifling" , "Oppressively humid" , "close" , "Warm and wet" .)