A hard freeze warning will be in effect from midnight Friday night to 9 a.m. Saturday across much of Arizona.
The areas projected to be affected are in southeast Pinal County, including the cities of Tucson, Green Valley, Marana, Vail, Mammoth and Oracle.
Widespread temperatures at or below 28 degrees are expected, with sub-freezing temperatures expected for several hours.
These conditions could kill unprotected and/or sensitive plants and crops. Outdoor water pipes should also be wrapped, drained or allowed to drip slowly to prevent possible bursting. It is also advisable to shelter outdoor pets inside.
Phoenix has also been issued a freeze warning, but is not expected to combat a hard freeze.
Temperatures are expected to climb back above freezing levels by 9 a.m. Saturday.