A lot of people may not realize, though, that Washington averages more rain than those cities even in a normal year. The average annual rainfall amounts in Seattle and London are 37 and 23 inches, compared with Washington’s 40 inches.
Seattle and London have gained their reputations as rainy cities because of the number of cloudy, damp days they pile up. Their rain typically falls gently, compared with that in Washington. Yet this month, Washington is not only outranking Seattle in rainfall but also in the number of gloomy, overcast days. In September, Washington has seen 13 cloudy days while Seattle has notched six.
While it’s a somewhat low bar to surpass the rainfall in Seattle and London, Washington has also managed to outdo tropical locations to the south that usually experience heavier downpours and higher annual rainfalls. For example, it has logged substantially more rainfall than even New Orleans, Charleston and Houston. These cities average about 64, 51 and 50 inches of rain, compared with Washington’s 40 inches but this year have 42.63, 40.13 and 38.36 inches compared with Washington’s 48.64 inches (through Monday).
While Washington has observed lots of rain this year, it is not alone. It has a number of peer cities that have seen comparable amounts, including:
- Roanoke: 45.09 inches
- Jacksonville, Fla.: 47.35 inches
- Richmond: 47.97 inches
- Harrisburg, Pa.: 48.34 inches
There are also U.S. cities that have been even soggier than Washington, including:
- Charlottesville: 50.95 inches
- Williamsport, Pa.: 52.92 inches
- Baltimore: 52.78 inches
- Louisville: 53.07 inches
- Miami: 54.07 inches
- Biloxi, Miss.: 57.85 inches
- Wilmington, N.C.: 86.5 inches
A map of the difference from normal rainfall over the Lower 48 (see below) shows how the Mid-Atlantic states have experienced some of the greatest rainfall surpluses along with pockets of the Southeast and Upper Midwest. The West, by comparison, has been quite dry.
As Capital Weather Gang’s Ian Livingston discussed last week, a major cause of the abnormally wet weather in the Mid-Atlantic is a strong, persistent high-pressure zone that has been parked over the Northeast. The clockwise flow around it has continuously funneled moisture off the Atlantic Ocean into the region.