AccuWeather has the story by Alex Sosnowski, Expert Senior Meteorologist
The chilliest air since last spring will sweep into part of the northern U.S. and neighboring Canada, bringing the first frost of the season to some locations.
A large area of high pressure will build southward from northern Canada and will roll into the northern Plains, Midwest and Northeast U.S. this week.
The much cooler air will first pour into the northern Plains and Canadian Prairies today into Tuesday and will spread into the Northeastern U.S. during the second half of the week.
The forecast magnitude of the chilly shot and the overall high pressure area is a little early for the time of year but has happened before.
The average date of the first frost or freeze is just that, an average.
I will be following up with news stories on the agricultural impacts of this first frost at the Freezes Tab above. It may be an early late frost in some locations. Stay Tuned.