WASHINGTON — On June 14, 1989, the skies darkened across the District around 3:30 p.m. A downburst from a powerful thunderstorm in Chevy Chase and Northwest DC took out dozens of trees and power lines. Some homes in Northwest and Chevy Chase were without power for up three weeks.
As strong as those winds were that day, what caused massive trees to be uprooted was the wet May. The region received over seven inches of rain in May of 1989. Officially 7.77” of rain fell at National, which marked it as the sixth wettest May, at the time.
May of 2008, now in third place with over 10 inches of rain, May of 2018 (8.73") and May of 2009 (8.05") actually pushed May 1989 down into eighth place. By comparison, May averages only 3.94" of rain in the nation's capital according to the climate records at the National Weather Service.
The first half of June 1989 was also rainy with 2.61" at National through June 13. June finished with over 6" of rain in DC, including the 0.80" with the infamous June 14 severe weather.
Flag Day storm of 1989
Winds in excess of 80 mph (Hurricane-force winds are 74 mph and up) had no trouble uprooting mature trees in Chevy Chase and Northwest.
One estimate calculated that nearly 10% of all mature trees in a certain area of Northwest were taken down by the downburst.
Damage was estimated at over $28 million.
We tracked the storm with our live Doppler radar (yes Channel 9 had live Doppler back then) showing the areas and neighborhoods that would be hit the hardest from the winds.
Many residents thought the damage was from a tornado. Downburst winds can leave a circular pattern of damage as the winds spread out.
Would the Flag Day thunderstorms have uprooted as many trees without that rainy May and start to June? No, but it was still a severe storm that would have at the very least taken some trees down as well as numerous tree limbs.