A weather station at Washington National/Reagan Airport, one of 64 Automated Surface Observing Systems (ASOS) in the U.S. that records official temperatures for the National Oceanic and Atmospheric Administration (NOAA), might not be accurate.

Meteorologist Anthony Watts, who blogs at Watts Up With That? says a reader alerted him to an 18-degree jump in temperature recorded by the DCA weather station on May 28 – in the middle of the night, after a thunderstorm. The reported high of 87.1 degrees at 12:25 a.m. was the official temperature reading for Washington, even though a nearby weather station at Andrews Air Force Base didn’t show a similar jump in temperature.