May 2015: Wettest Month Ever Recorded in US

When it rains, it pours – this old adage was literally proven to be true last month. With national weather data dating back to 1895, May 2015 was the wettest month ever recorded in the contiguous United States.

According to NOAA, an average of 4.36 inches of rain fell across the lower 48 states, which is 1.45 inches above average. The vast majority of this impressive total came down in the southern plains. Colorado experienced its wettest May on record. Texas and Oklahoma each had their single wettest month ever, with rain totals that were more than twice their respective long-term averages.

For people living on the either the west or east coasts of the country, this news may come as a bit of a surprise. California continues to be plagued by a devastating drought and many states along the eastern seaboard saw drier than average conditions for the month with six states recording a top-ten driest May.

While the torrential rain in the south central US caused deadly and destructive flooding this spring, it also abruptly ended the region’s multi-year drought. Nationally, the latest report from the US drought monitor shows that only 24.6% of the country is in some form of drought. That is down from 37.4% at the end of April. It is also the smallest national drought footprint since February 2011.

There were many factors that contributed to May’s excessive rainfall, including El Nino – a natural oceanic-atmospheric phenomenon that tends to bring wet weather to the southern part of the country. However, the National Climate Assessment, a US government report that came out last year, says that climate change has caused heavy rain events to become heavier and more frequent across most of the US. Experts expect this trend to continue, but as we saw last month the distribution of rainfall is not likely to be equal.

Credit: NOAA

Credit: NOAA