We cooled down by swimming in the river.

我们在河里游泳，好凉凉。

Thank heavens, it's cooled off a little.

谢天谢地, 天气总算凉了。

After canicule, autumn will soon come, and it'll be much cooler.

过了三伏，秋天就到了，就凉很多了。

It will be cooler when the sun has set.

太落山之后会凉。

We could get some coolness here.

这儿凉。

Keep in the shade; it's cooler.

你就在阴凉吧, 那儿比较凉。