The National Oceanic and Atmospheric Administration reported the month of May was the second wettest, and temperatures were in the bottom third for 125-year U.S. history.

The 2010 publication, titled "A Global Overview Of Drought and Heat-Induced Tree Mortality Reveals Emerging Climate Change Risks for Forests" was accepted by the Obama administration as scientific evidence that climate change had made the Earth "increasingly vulnerable to higher background tree mortality rates and die-off in response to future warming and drought, even in environments that are not normally considered water-limited."

But NOAA just reported that May U.S. precipitation totaled an average of 4.41 inches, 1.50 inches above average, and ranked second wettest in the 125-year period of record for May as well as second wettest for all months since January 1895.  The only wetter month in U.S. history was May 2015 with 4.44 inches of precipitation. 

The 37.68 inches of precipitation across the contiguous U.S. from June 2018 to May 2019 shattered the previous 1982–83 12-month period by 1.48 inches.  Near-record to record precipitation was observed from the West Coast through the central Plains and into the Great Lakes and parts of the Northeast.

As a result, severe May flooding was observed along the Arkansas, Missouri, and Mississippi rivers.  Vicksburg, Miss. reported ongoing flooding since mid-February.

A southward dip in the jet stream over the western contiguous U.S. during May contributed to above-average late-season snowfall, with Denver reporting its snowiest May in 44 years with 3.9 inches total for the month.  Duluth, Minn. reported 10.6 inches of snow on May 9 for the snowiest day since records were first kept in 1884.

May's average contiguous U.S. temperature was 59.5°F, 0.7°F below the 20th-century average and ranking in the bottom third of the 125-year record.  Below- to much-below-average temperatures spanned from California into the Great Lakes and across New England.  Five states, from the Southwest to the northern plains, had a top-10 coldest May on record.

The first five months of 2019 were marked by large regional temperature variability, but average temperature for the contiguous U.S. was 43.4°F, 0.1°F above the 20th-century average and ranking in the middle third of NOAA records for the January-to-May period.