The rain was pouring down.

雨在倾盆而下。

《柯林斯英汉双解大词典》

Ahead was the deep V of a gorge with water pouring down it.

前面是陡深的V字形峡谷，水流倾泻而下。

《牛津词典》

Look! It's pouring down outside.

看！外面就要下起雨来了。

youdao

The rainforest made good on its name, pouring down until we hacked through the underbrush into a canopy-covered lagoon.

BBC: Taming the heart of the Peruvian Amazon

The Rangers are trying to bear down, which means they don't listen to the advice pouring down from the stands.

WSJ: Rangers Nab Shootout Win

With the rain absolutely pouring down in Coleraine, Macheda did add the third nine minutes into the second half as he hammered past Pacheco.

BBC: United win Milk Cup premier title