It may rain; you'd better take an umbrella just in case.

可能下雨，拿把伞吧，以防万一。

《新英汉大辞典》

That it may rain?

又想到过天可能下雨吗？

youdao

It may rain, you'd better take an umbrella (just) in case.

天可能会下雨，你最好带把伞以防万一。

youdao

More than thirty centimeters of rain fell on May first and second.

VOA: special.2010.05.17

Rain may soon appear. A wise person copies the farmer.

VOA: special.2010.01.31

That does not sound like much but it does mean that extreme rain storms may bring more rain than before - with more moisture in the air, what goes up must come down, and the odds are worse.

BBC: Why, oh why, does it keep raining?

Then take care and may the rain fall soft on you, the woman said.

NEWYORKER: The Insufferable Gaucho

There may be rain in the morning, then sun later.

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