This is the adjective form of hot... but we're going to call it hot weather. Why? Because there's a difference between something that's hot and the weather or atmosphere being hot. This is that kind of hot, as in..."Damn, man, it's hot out here!"
This uses the same reading as the one you learned with the kanji, so you're good to go here!
It's so hot I'm about to melt.
It has been hot these days in Japan.
It’s too hot and humid! I can’t sleep in this heat. Let’s go to the pool!