Forget April Showers: This May Was the Wettest Month in U.S. Records

Last month was the wettest on record for the contiguous United States, according to federal meteorologists.

On average 4.36 inches of rain and snow — mostly rain — fell over the Lower 48 in May, sloshing past October 2009, which had been the wettest month in U.S. records with 4.29 inches. National Oceanic and Atmospheric Administration records go back to 1895. NOAA climate scientist Jake Crouch calculated that comes to more than 200 trillion gallons of water in May.

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Crouch said the record was triggered by a stalled pattern of storms that dumped massive amounts of rain in the central U.S., especially in Texas and Oklahoma, which had their rainiest months. Oklahoma and Texas had been in a five-year drought, and it was washed away in just one month, Crouch said: "It's like one disaster ending a catastrophe."

Colorado had its rainiest May on record. At the same time, parts of the Northeast were unusually dry.

Crouch said the El Nino weather pattern, which starts with warming in the central Pacific, is usually associated with heavy rainfall — but it's too early to say if the current El Nino triggered the record moisture. More frequent downpours also are expected as the world warms, but Crouch said there's no way to connect climate change to a single soggy month.