While a surge in warmth and humidity will lead to downpours and gusty storms in the northeastern United States into early Saturday, much cooler air will soon follow.
Daytime temperatures will climb well into the 80s F and can reach 90 in some of the major cities, even where the sun is only out for a few hours or less into Friday.
The air will feel quite humid following a couple of days of cool conditions. South-to-southwesterly breezes will create a tropical environment.
The tropical air will set the stage for drenching showers and locally severe thunderstorms to close out the week.
Some communities from the lower Great Lakes to the Atlantic coast can be hit with a thunderstorm packing strong wind gusts.
In addition to the locally severe thunderstorm threat will be the potential for downpours that are intense enough to cause flash and urban flooding.
While these downpours can occur with any shower or thunderstorm throughout the Northeast into Saturday morning, there is a zone that may be at greater risk for flooding.
"As moisture from Tropical Rainstorm Cindy sweeps through areas from southern Pennsylvania and central New Jersey to Maryland, Delaware, West Virginia and northern Virginia could have a period of torrential rain from later Friday night to Saturday morning," according to AccuWeather Senior Meteorologist Dave Dombek.
"People traveling in these areas should anticipate weather-related delays," Dombek said.
Northeastern US to turn unusually cool during late June
Much cooler air will sweep across the Great Lakes and into the Northeast as the weekend progresses. This push will end the risk of downpours in the coastal areas, the Appalachians and the Ohio Valley.
Spotty showers and thunderstorms are likely to pop up around the Great Lakes.
"The air may get cool enough to allow a couple of waterspouts to form over the Great Lakes, especially over Lake Erie from Sunday to Monday," Dombek said.
Along with lower temperatures will be a substantial drop in humidity levels. The less humid air will not only be felt to the New England and mid-Atlantic coasts, but also in much of the Southeastern states.
"Temperatures and humidity levels will likely stay below average from later this weekend through the middle of next week," according to AccuWeather Long-Range Meteorologist Max Vido.
There are no signs of heat returning and staying for an extended period through the first part of July.
"Instead, it looks like pattern favoring back-and-forth warm and cool days with only a brief spike in heat for a day or two into the first week of July," Vido said.
The extensive swath of cool air with low humidity will translate to lower electricity usage when compared to average for late June and early July, since the demand for air conditioning will be less.
Most days will still be warm enough for swimming and other summer outdoor activities.