I'm melting!
夏天太热的时候都有这种感觉，就是自己热得快化掉了。

The heat is blistering already, and women in the crowd shade themselves from the sun with plastic bags。
有时候夏天会热得让人觉得窒息，blistering就是形容那种热到让人觉得难受的大热天。

Let's not go to the movies, it's stifling out there.
Stifle本身有窒息的意思，形容那种不仅高温而且让人喘不上来气的天气，即又热又闷。

Looks like another scorcher day, how are we gonna get through the next three months?
天会下雨，也可以下火，形容这种火炉般天气的词是scorcher。

It's hot as heck!
因为太热而产生的抱怨，heck比hell要礼貌一些，更温和版本的抱怨。

It's like a hundred degrees in there.
夏天的时候阳光直射，如果走进一个没开空调的屋子，可以用这个句子来表达夸张的心情。

It's sizzling hot today, I don't feel like playing basketball.
石锅饭刚刚上桌的时候听到嘶嘶的声音，天气热到你感觉地面都要冒烟的时候，打篮球也许不是个好主意。