phrasal-verb
set in
当像雨或寒冷这样的不愉快的事情开始并且似乎可能会继续下去时
Meaning
when something unpleasant like rain or cold begins and seems likely to continue
Example
The cold season has **set in**, and we need to wear warm clothes.
寒冷的季节已经**set in**,我们需要穿上暖和的衣服。