Hot And Humid
Humid
い adjective
If it’s a steaming hot day, it means the weather is hot and humid (or you can just say humid, because that usually implies hotness too). This is a useful word for summers in Japan, since you'll complain about this all the time.
The reading comes from 蒸れる and 暑い. Know those and you know this too.
今年の夏は絶対去年よりも蒸し暑いよね。
This summer is definitely more humid than it was last year.