用英语怎么说天太热

"It's too hot" is a common way to express that the weather is hot and uncomfortable.
"Too" is an adverb used to indicate a higher degree or level than is desirable or acceptable. In this sentence, it modifies "hot" to indicate that the temperature is higher than the speaker finds comfortable.
Examples:
"I can't go for a walk, it's too hot outside." (外面太热了，我不能出去散步。)
"I need to turn on the air conditioning, it's getting too hot in here." (我需要打开空调，里面太热了。)
"I wish I had a cold drink, this heat is making me too hot." (我希望我有一杯冷饮，这热天让我太热了。)