The first cold nights in Arizona, station by station
When the first night of 50°F or colder and the first freeze usually come at each reference station over the last 10 falls (a count shows where some years never got there), with the coldest week from NOAA’s 1991 to 2020 normals and the coldest night of the last 10 winters.
First cold nights and the coldest week at Arizona reference stations
Station
First 50°F night
First freeze
Coldest week
Coldest night, last 10 winters
PhoenixPhoenix Sky Harbor International Airport, USW00023183
Nov 15
Jan 2 (1 of 10 winters)
Dec 20 to 26normal low 44°F
30°FJan 2, 2019
TucsonTucson International Airport, USW00023160
Oct 28
Dec 18 (9 of 10 winters)
Dec 21 to 27normal low 40°F
24°FJan 23, 2025
FlagstaffFlagstaff Pulliam Airport, USW00003103
By Jul 1
Oct 2
Dec 18 to 24normal low 16°F
−9°FFeb 16, 2023
Normals from NOAA NCEI; nightly lows from GHCN-Daily, the winters of 2016 to 2017 through 2025 to 2026.
The panel at the top of this page sets the next 7 nights at Phoenix against the normal low for each date and adds the Climate Prediction Center outlook for the two weeks after. Enter a ZIP for your own town; it uses the nearest of the 3 Arizona reference stations.
The first night of 50°F or colder is a fair marker of the first real front. At Phoenix the first night of 50°F or colder came around Nov 15 in the median of the last 10 falls, as early as Oct 27 in 2020 and as late as Dec 5 in 2017. Elsewhere in the state: Tucson around Oct 28 and Flagstaff by Jul 1.
Phoenix has a freeze in only 1 of the last 10 winters, on Jan 2, 2019, counting nights at 32°F or colder over the last 10 winters. Across the state: Tucson around Dec 18 (9 of 10 winters) and Flagstaff around Oct 2.
The coldest night of the last 10 winters at Phoenix was 30°F on Jan 2, 2019, and the coldest night of a typical winter there was 36°F. Elsewhere: Tucson 24°F on Jan 23, 2025 and Flagstaff −9°F on Feb 16, 2023. The record at the Phoenix station is 17°F, on Jan 5, 1950, in daily records since 1933.
Each night's forecast low is compared with the NOAA normal low for that date at the nearest reference station. A night 20 or more degrees below normal is an arctic blast, and so is a night below zero where the normal low is 10°F or warmer. A night 10 to 19 below is a cold snap. A night 5 or more below, or a week that runs 3 or more below on average, is colder than normal, and a week 5 or more above is mild.
The normal lows and coldest weeks are NOAA's 1991 to 2020 daily climate normals for Phoenix Sky Harbor International Airport (USW00023183), Tucson International Airport (USW00023160) and Flagstaff Pulliam Airport (USW00003103). The recent winters, first dates and records come from the same stations' daily lows in NOAA's GHCN-Daily archive, the winters of 2016 to 2017 through 2025 to 2026. The 7 night forecast is the National Weather Service's and the outlook is the Climate Prediction Center's.
