May 2021 marked the first time in more than 70 years that the U.S. has not seen a tornado rated stronger than an EF3 on the Enhanced Fujita (EF) Scale.
In a Twitter announcement detailing the extent of severe weather during the month, the National Oceanic and Atmospheric Administration (NOAA) wrote that May reports were "below normal," though tornado reports were near the 10-year average.
"May 2021 had the 8th fewest tornado watches since 1970," the agency said in a thread.
"Thus far, only 8 EF2+ tornadoes have been confirmed in May 2021. If no additional significant tornadoes are added, this would be the 5th fewest May significant tornadoes in recorded history (1950-present)," it added.
NOAA data shows that the May average from 1991 to 2010 is 276 tornadoes and the 2011 to 2020 average is 272. In May 2021, the U.S. saw 289 preliminary tornado reports.
Conversely, severe weather reports were 720 reports below the 2011 to 2020 average: down to 2,756 from 3,476.
For the first time in seven years, the U.S. had no tornado fatalities in May – a relief for Gulf Coast and Southern states accustomed to unprecedented amounts of tornado activity.
May 2020 saw a record 13 straight days with at least eight or more tornado reports, according to AccuWeather.
The outlet also noted that while no EF5 tornadoes have been reported in the U.S. for more than eight years, some meteorologists believe tornadoes have been underrated by the National Weather Service.
As to the reasoning for why May saw such low-rated activity, AccuWeather cited high temperatures that have swept the country at the beginning of summer, highlighting that tornado numbers typically drop in the hotter months of the season.