Some Midwesterners will wake up to the first frost and freeze of the season this week, while others around the northern Great Lakes may witness the first snow flakes of the season.
Drastically colder air is surging into the Midwest behind a cold front, allowing temperatures to plummet by 20-30 degrees.
Clear and calm conditions behind the front will allow for temperatures to drop near and below freezing across eastern portions of the Dakotas, Minnesota, northern Iowa and northwestern Wisconsin early Tuesday morning.
Fargo, N.D., Aberdeen, S.D., International Falls and Duluth, Minn., are among the cities and towns that will have their first frost or freeze of the season.
Any outdoor plants in pots should be brought inside, gardens should be protected and scrapers should be handy for frosty windshields.
On Wednesday morning, colder air will reach even farther south and east. There is potential for a frost as far south as northern portions of Illinois.
With chilly air moving across the very warm water of the northern Great Lakes, a few snow flakes could fly or mix in with rain showers around the Upper Peninsula of Michigan on Tuesday night. According to the National Oceanographic Data Center, water temperatures are still in the lower 60s in Lake Superior.
While no snow accumulations are expected, seeing snow flakes may catch some off-guard so early in the season.
A new tropical threat may loom for the Caribbean and North America in the not-too-distant future, while eight more weeks remain in the Atlantic hurricane season.
The greatest danger of flooding across the central United States will unfold in western Texas, where downpours will be most persistent into Monday.
Fall air has finally arrived in the northeastern United States and may yield the first frost of the season in parts of the region this weekend.
Typhoon Megi will continue to strengthen before threatening lives and property across Taiwan and eastern China this week.
Gusty winds will accompany a push of chilly air across the Great Lakes from Sunday night through Tuesday.
The first windstorm of the season could blast the northern United Kingdom around Tuesday as Karl arrives.
Arthurdale, PA ()
Golf-ball sized hail up to 8" deep.
Baltimore, MD (1816)
Water froze one-half of an inch thick.
El Cordnazo, CA (1939)
Greatest September rainstorm with 5.42 inches in 24 hours at L.A. Floods killed 45; $2 million damage.