Washington, D.C., Philly and New York City face flash flood risk into this weekend
Along with areas of severe weather, heavy rain will create high risk of flash flooding in parts of the eastern United States into this weekend, including major mid-Atlantic cities.
Severe thunderstorms drenched much of the Northeast on Aug. 20, but parts of Delaware, Pennsylvania and New York were hit especially hard.
Thunderstorms will cause problems through this weekend in the central and eastern United States, including through the Interstate 95 corridor, but torrential downpours and flash flooding may have a more far-reaching impact along the Atlantic Seaboard as cooler air slowly expands from the Upper Midwest.
Some thunderstorms will become severe from the Plains to the Eastern states in the coming days, and thunderstorms in any of these zones can produce flooding downpours.
However, there is an area centered on the mid-Atlantic states where multiple rounds of rainfall could occur into Sunday.
This image, captured on Friday morning, Aug. 21, 2026, shows a non-tropical storm with an eye swirling over the Atlantic, southeast of New York City and valley fog over the Appalachians in Pennsylvania and New York. The storm was responsible for the flooding rain in the mid-Atlantic and southern New England from Thursday to Thursday night. (AccuWeather Enhanced RealVue™ Satellite)
As a jet stream dip expands, disturbances in the jet stream are expected to support thunderstorm development and torrential downpours. These areas of downpours will move slowly and can produce a couple of inches of rain in as little as an hour.
Drenching rain and thunderstorms already brought 1-3 inches to much of the mid-Atlantic on Thursday, with localized amounts of 4 inches across far eastern Pennsylvania, northern New Jersey, southeastern New York and western Connecticut.
Subsequent rounds are forecast to develop this weekend and cross some of the same areas that received torrential rain on Thursday and Thursday night.
Dozens of major metro areas can be affected by flash flooding in the eastern quarter of the nation into this weekend, with the zone from Washington, D.C., to New York City at a heightened risk.
Small streams and drainage canals can surge quickly, flooding unprotected secondary roads and neighborhoods.
In situations like this, storm drains can be overwhelmed, causing street, highway and subway station flooding. Most of the activity will focus on the afternoon and evening hours. However, there may be some exceptions where torrential rainfall occurs late at night and lingers past daybreak.
Some of the storms around the Great Lakes could bring waterspouts and small hail through this weekend.
Enough dry air may sweep in to end the threat of downpours or greatly reduce the duration and extent of showers and thunderstorms west of Interstate 95 in the mid-Atlantic on Sunday. There may still be intense downpours that redevelop along the immediate coast and in New England to close out the weekend.
Travelers along the Atlantic Seaboard should expect delays due to severe thunderstorms and torrential downpours, which can reduce visibility and, in some cases, block travel.
The core of the cool air associated with the jet stream dip will be centered over the Great Lakes and the interior Northeast this weekend into early next week, where daytime highs will be 5-10 degrees below the historical average for this time of year.
Heat on hiatus in Upper Midwest, Northeast
Areas along the East Coast and right next to the warm Atlantic may experience temperatures only a few degrees below average by early next week. However, the pattern will prevent any long-lasting heat through the end of August.
Cloud cover will tend to reduce the extent of nighttime and early-morning fog. However, when the sky clears, moist ground can lead to locally dense fog, especially along lakes and rivers.
Those seeking heat and sunshine are advised to head to Texas and the South Central states in the coming days, where widespread highs in the mid-90s to low 100s are forecast.
However, from the Upper Midwest to the Northeast, don't expect any heat waves through the remainder of August. In fact, it will be downright chilly in some areas away from the Atlantic coast.
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