The final month of fall is beginning on a chilly note as the coldest air so far this season spreads across the central and eastern United States through the weekend.
Many cities east of the Mississippi River endured one of their warmest Octobers on record, but much colder temperatures have now replaced that mild air.
The chilly air will continue to expand farther south and east on Wednesday, with highs 10 to as much as 25 degrees below average from the Central and Southern Plains to the East Coast.
High temperatures will be stuck in the 40s and 50s from North and West Texas to the western Carolinas, as highs struggle to get out of the 40s across the Texas Panhandle, Oklahoma, Arkansas, northern Mississippi, western Tennessee, Missouri and Kansas.
Temperatures will also be in the 40s Wednesday across the entire northern tier of the nation from the Northern Plains to the Midwest, Ohio Valley and interior Northeast, with the 50s expected along the Interstate 95 corridor.
On Thursday, the core of the colder-than-average temperatures will settle across the nation's southern tier. Highs will be 10 to 20 degrees below average from the Southern Plains to the Southeast, translating to temperatures mainly in the 50s, with any 60-plus-degree highs confined to areas along the Gulf Coast.
If Houston fails to reach 60 degrees on Thursday, it will be the first high in the 50s there since Feb. 19 (51 degrees).
In the Midwest and Northeast, highs will mainly be in the 40s on Thursday, though a few spots along the coast or farther south into the mid-Atlantic may reach the lower 50s.
The colder-than-average temperatures will be most widespread in the Southeast on Friday. Highs will range from 10 to 20 degrees below average from northern Florida and the Gulf Coast into much of Virginia.
Many of these areas will see highs in the 50s Friday afternoon, but most of North Florida and the Panhandle should still reach the lower to mid-60s. It will likely be the coolest day in Tallahassee, Florida, since April 2, when the high was 63 degrees.
The Midwest and Northeast will have temperatures 5 to 10 degrees colder than average on Friday, translating to highs mainly in the upper 40s and lower 50s.
Low temperatures will dip below freezing in many areas the next few mornings.
The National Weather Service has issued Freeze Watches, Freeze Warnings and Frost Advisories from Wednesday night into Thursday morning from the Texas and Oklahoma panhandles and southern Kansas into parts of the mid-Mississippi Valley, mid-South and lower Ohio Valley.
Freeze Watches, Freeze Warnings and Frost Advisories are also posted for parts of the Northeast from Wednesday night into Thursday morning. These include areas from northeastern New Jersey into the lower Hudson Valley, southern Connecticut and central and eastern Long Island.
The season's first frost or freeze marks the end of the growing season, so if you have sensitive vegetation that you want to keep around a little longer, you're advised to cover it up to protect it from the cold temperatures.
Frosts and freezes will remain a risk Friday and Saturday mornings, especially across the interior.
However, even areas along Interstate 95 from Boston to Washington could see some patchy frost Friday night into early Saturday.
While the Northern and Central Plains and the upper Midwest will see a warming trend late this week, the colder-than-average temperatures are expected to continue in the eastern states through the weekend.