Dark rain clouds were coming over so he went home to find his Mum.

乌云来了，索尼尔只好回家去找妈妈。

youdao

Dark clouds means rain.

乌云意味着要下雨。

youdao

It's so dark. Perhaps it's going to rain.

天这么黑，许是要下雨吧。

《新英汉大辞典》

Friday started out stormy, but as the 14 soldiers, Marines and their families boarded a yacht for a sightseeing cruise around lower Manhattan, the dark rain clouds parted giving them a glorious view of the Statue of Liberty.

VOA: standard.2009.08.01

The twenty-two men rested until dark, listening to rain hit the roof of the farm house.

VOA: special.2009.06.18

On 5 January 1976, the 10 textile workers were travelling home from work in the dark and rain on a minibus in the heart of rural County Armagh.

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Back home, they had to deal with an utterly flat landscape laced by rivers and canals much of it below sea level, reclaimed by dikes forever loomed over by dark gray clouds, damp mists, and rain or snow.

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Most of all, there is nothing as satisfying as those moments where you step out on a dark night, the wind blowing, the rain beating down, with a long journey ahead - and decide to catch the Tube instead.

BBC: NEWS | UK | Magazine | Cycle warriors