Typical English weather—one minute it's raining and the next minute the sun is shining.

典型的英国天气，时雨时晴。

《牛津词典》

It's raining cats and dogs.

下大雨了。

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It's raining worse than ever.

雨下得比以往都大。

《牛津词典》

"It's" with an apostrophe is short for "it is," as in "It's raining."

VOA: special.2010.02.11

It's really, in a sense, the physical image is of rain; it's raining, so it's leaking all over it.

这在某种意义上确实是，下雨的一种具体的描述;,因为在下雨，所以天空像是在漏水。

耶鲁公开课 - 1945年后的美国小说课程节选

It's raining outside.

外面下着雨呢。

Is it okay 实战 - SpeakingMax英语口语达人

They'll look outside and see a blue sky... and the airline will say, 'Well, it's raining in Dallas or Atlanta.

BBC: How to minimise the effect of travel disasters

If 90% of cars on one stretch of highway have their wipers on full blast, they could know it's raining heavily.

FORBES: Magazine Article

His 2004 album It's Raining sold 1m copies and he appeared in several movies, including Hollywood production Speed Racer in 2008.

BBC: South Korean singer Rain in military service row