不是介词，hot是形容词，意思是热的，例如：

1、On such a hot day， even water was nectar.这么热的天，清水都是甘露。

2、He likes his tea neither too hot nor too cold.他想要杯不凉不热的茶。

3、They are one of this year's hot new bands.他们是今年走红的新乐队之一。