I lived through some very hot summers in Israel and found the heat brought forth the most amazing smells from plants, fruits and tractors and the hair on people's heads.
also the smell of a fresh t-shirt & short every morning was a real pleasure ...
and now I just need to go and take that sun in out there
Fresh cut grass, various Agricultural smells, and that particular dry peaty smell you get from bog streams in the summer.
Also, the smell of heather and the sea remind me of holidays.
And the smell of Cold Bulmers/Magners splashing over ice cubes in a pint glass, in a beer garden, surrounded by friendly, and scantily clad young ladies.