She gets very bad-tempered when she's tired.

她累的时候就爱发脾气。

《牛津词典》

I don't know what's got into him recently; he's become very bad-tempered.

不知道他最近怎么了，脾气变得坏极了。

youdao

His boss is rude and very bad-tempered. And the five people who work for Mike are lazy and untrained so Mike has to explain everything to them.

麦克的上司很粗鲁而且有个坏脾气，麦克的底下管着的五个人又懒又磨蹭，所以凡事都需要麦克去解释。

youdao

So the budget negotiations could become very bad-tempered and there is no guarantee of success.

BBC: Poland's continuing claim on EU investment funds