This video shows why cooler air is coming to the Northeast (with the exception of some coastal spots where the westerly winds will be a bit warmer than the ocean winds were during the weekend).
This map shows the pressure analysis for the Northeast and Great Lakes. The gusty flow on the west side of the low pressure (where the lines are closest together) area adds a real autumn feel to the air.
Thunderstorms were widespread yesterday and last night as near-ground air was warm and humid while the air aloft was cooling.
More than 184,000 lightning strokes are plotted.
After reaching the 80s today from NYC to Boston, it might not be that warm again through much of next week.
A noticeable push of cooler air will spread southward from Ontario and Quebec into the eastern Great Lakes and New England between tomorrow and Saturday.
A cold front from eastern Canada will slide southward along the East coast between late Friday and the end of the weekend. For the area from Philadelphia to Boston, where temperatures will reach the summery 80s each day through Friday, it will mean a noticeable change to cooler weather.
Average high temperatures in Chicago and New York City are in the mid-70s now, but for the next several days, temperatures will run 8-15 degrees above those long-term averages. Supporting this warmth is a flow aloft that originates over the Southwest:
Rain was common in the Northeast this morning, though Boston was still waiting as of 9 a.m. Their summer dry spell has continued.
There will be an increase in warmth and humidity in the Northeast that will not be reversed until the next cold front arrives.