A sudden and sharp drop in temperatures has triggered freeze warnings in 16 states across the US, stretching from the Northeast and Midwest to southern and western states, as cold air rushes across the country at the start of the season.

The National Weather Service warnings apply to millions of residents. They urge them to take precautions to protect endangered plants, outdoor spaces and animals.

“Frost and freeze conditions could kill crops and other sensitive vegetation,” NWS advises. “Take steps now to protect sensitive plants from the cold. Additionally, freezing weather could also “damage unprotected outdoor installations.”

Temperatures are expected to fall below freezing in many areas, a stark contrast to the warmer than average fall conditions of recent weeks.

According to the NWS, a freeze warning is issued when temperatures are expected to remain below 32 degrees Fahrenheit for an extended period of time.

Newsweek I emailed the NWS for comment on Friday.

The freeze warnings cover a wide area of ​​eastern states including Maryland, Washington, DC, Virginia, West Virginia, Pennsylvania and New York. Northwestern North Carolina will also be affected.

The freeze warning remains in effect in Maryland, Washington County, Virginia and West Virginia until 9 a.m. EDT Friday. Subfreezing and freezing temperatures are expected in portions of southwest and west-central Virginia and northern and southeast West Virginia.

Parts of northwest, southwest and western Pennsylvania are under a freeze warning from 2 a.m. to 9 a.m. EDT Friday, with temperatures reaching 29 degrees.

A frost warning is in effect for a portion of east-central New York until 9 a.m. EDT Friday, and freezing temperatures as low as 28 degrees are expected.

Western states such as parts of Nevada, Oregon, Arizona, Utah, California, Idaho, Washington and Wyoming will also be affected.

Central, north-central, northwest and south-central portions of Wyoming are under a freeze advisory from 11 p.m. Wednesday through 10 a.m. MDT Saturday, with freezing temperatures expected to reach 21 degrees.

Temperatures will be below freezing in parts of Nevada and California, reaching lows of 20 to 28 degrees. Temperatures of up to 30 degrees are forecast in the Oregon valleys, and a freeze warning is in effect in all three states until 9 a.m. PDT Friday.

There are two freeze warnings in effect for Arizona. The first is Saturday from 1 a.m. to 9 a.m. MDT, with below freezing temperatures expected. Temperatures of up to 35 degrees are expected for the second frost warning on Sunday from 1 a.m. to 9 a.m. MDT. Affected areas include the Upper Gila River Valley and Eastern Cochise County.

A wind warning remains in effect for parts of the state.

A freeze warning is in effect in Utah until 9 a.m. MDT Friday, with widespread temperatures below 32 degrees. In the Sanpete and Sevier valleys temperatures are only 22 to 26 degrees. A Freeze Advisory is in effect for Eastern Box Elder County, Utah Valley and Western Uinta Basin from 8:00 p.m. Friday to 10:00 a.m. MDT Saturday.

Utah was one of three states to issue a winter storm warning earlier this week. The storm is expected to bring heavy snow and strong winds to mountainous areas of the western states.

Freeze warnings are also in effect for parts of the Midwest, including Ohio and Idaho. In Ohio, the warning is in effect Friday from 2 a.m. to 9 a.m. EDT and affects Geauga, Mahoning, Portage and Trumbull counties, as well as inland Ashtabula County.

A freeze warning is in effect in Idaho from 3 a.m. to 9 a.m. MDT Friday and freezing temperatures as low as 29 degrees can be expected.