Dangerous storms threaten to ruin outdoor plans and wreak havoc on the evening commute across the eastern Great Lakes and Northeast.
Very hot and muggy air will help to fuel the thunderstorms with temperatures climbing well into the 80s and 90s.
At least a couple of zones of nasty thunderstorms are expected to develop with the heating of the day encompassing areas from lower Michigan, Ohio, Pennsylvania and upstate New York to Virginia, the Delmarva, coastal New York, New Jersey and part of New England.
Some of the storms will become severe, providing the threat for damaging wind gusts and hail. In a couple of instances a tornado can be produced by the strongest storms.
Detroit, Cleveland, Buffalo, Pittsburgh, Philadelphia and perhaps New York City could all be in the path of the damaging storms.
The strongest storms can produce wind gusts to 65 mph which is more than enough to knock down tree limbs and power poles.
While damaging winds appear to be the biggest threat, there can be large hail and flash flooding.
If threatening weather approaches, be sure to have a secure indoor location to move to.
Heed any watches or warnings and as always, check back with the AccuWeather.com Severe Weather Center.
Strong thunderstorms will shift farther east Monday evening, bringing a damaging wind threat to Rochester, Burlington, and perhaps Montreal. However, as the night progresses, thunderstorms will lose their intensity thanks to loss of daytime heating.
Hawaii will escape the worst, but not all of Guillermo's impacts as the tropical storm passes north of the islands Wednesday through Thursday.
A line of violent thunderstorms tore across Massachusetts, including the Boston area, Tuesday afternoon. Isolated severe thunderstorms will continue into Tuesday evening.
The Northeast will catch a break from heat and humidity for the remainder of the week.
Super Typhoon Soudelor in the western Pacific Ocean will remain a powerful tropical cyclone this week eventually threatening Taiwan and eastern China.
An area of low pressure spinning off the coast of the Carolinas is attempting to obtain some tropical characteristics.
Two spectators were killed and at least another 32 people were injured Monday evening, as strong storms forced a circus tent to collapse in Lancaster, New Hampshire.
Casper, WY (1990)
A total of 0.84" of rain. The normal rainfall for all of August is 0.63".
Alexandria, VA (1992)
80 mph wind gust from a thunderstorm.
Flathead Lake, MT (1995)
5-6 foot waves from a distant thunderstorm damaged boats, sea walls, and docks.