Hot Weather, Hot
い adjective
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!"
あつい
This uses the same reading as the one you learned with the kanji, so you're good to go here!
今日はとても暑いですね。
It's very hot today, isn't it?
日本では、このところ暑い日がつづいています。
It has been hot these days in Japan.
日本の夏は暑すぎるから、七月と八月はカナダに行くよ。
The summer in Japan is too hot, so I'm going to Canada from July to August.