Be careful if you have an outdoor fire or barbecue — make sure ashes are cold before leaving.

如果你在户外生火或烧烤，一定要小心，离开前一定要确保炉灰是冷的。

youdao

It's chilly outside; be careful not to catch cold.

外面有点冷，当心着凉。

《新英汉大辞典》

You ought to be careful about this kind of feverish cold, it often kicks back when you think you are better.

你应当对这种有发烧症状的感冒小心些，它常常在你以为好转的时候复发。

youdao

Home cocktailers should be careful, however, not to store their alcohol in extreme heat or cold for lengthy periods, he says.

WSJ: The Home Bar, Only Better