1. to rain fire 火辣辣的热，像在下火一样
When it's so hot that you feel like you're trapped in a furnace (熔炉)
Are you crazy? It's raining fire outside and you want to take a walk? (你疯了是不是？外面热得像在下火，你居然说要去外面散步？)
2. stifling 令人窒息的闷热
When it's so hot that it becomes difficult to breathe.
I hate having to work in such a stifling office! (我讨厌在这样一个闷热的办公室里工作！)
3. Africa-hot 像非洲一样热
Here, Africa is used as an adjective meaning extremely hot weather.
It's Africa-hot out there! I wouldn't step outside if you paid me 100 yuan. (外面太热了！就算你给我100块钱我也不会出门的。)
4. thermometer-breaker 温度计都要热爆了
When the weather is so hot that it feels like the thermometer could break.
I didn't want to run today. It's a thermometer-breaker (day). (我今天不想跑步了。这天气，温度计都快热爆了。)