Frost dates / Arizona / Phoenix

Frost dates in Phoenix, AZ

The station on this page is PHOENIX DEER VALLEY MUNI AP, AZ US (USW00003184), 8 miles from the city point. Population in the Census 2024 estimate is 1,673,164.

Zone 9bUSDA average annual extreme minimum 25°F to 30°F, from ZIP 85021 (0.8 miles from the city point used on this page).

Median last 32°F is January 8. Median first 32°F is December 25. The 50% growing-season length is 354 days. The green band runs from the median last frost to the median first frost. Thin ticks mark the 10%, 50%, and 90% dates.

Outside the median season Growing seasonTicks: 10%, 50%, and 90%

Last 32°F in spring

NCEI’s probability is the chance the last spring minimum of 32°F or lower occurs on or after the date.

Probability	Date	How to read it
90%	December 16	Earlier date. A last 32°F on or after this day is common.
50%	January 8	Median.
10%	February 12	Later date. A last 32°F on or after this day is uncommon.

First 32°F in fall

NCEI’s probability is the chance the first autumn minimum of 32°F or lower occurs on or before the date.

Probability	Date	How to read it
10%	December 5	Earlier date. A first 32°F on or before this day is uncommon.
50%	December 25	Median.
90%	January 23	Later date. A first 32°F on or before this day is common.

32°F growing-season length

Days between the last spring 32°F and the first autumn 32°F. The figure is a length the season meets or exceeds at that probability, from NCEI, not a subtraction done on this site.

Probability the season is at least this long	Days
10%	365
50%	354
90%	320

28°F threshold

	10%	50%	90%
Last, on or after	February 2	January 8	December 15
First, on or before	December 14	January 7	February 1
Season at least	365 days	365 days	359 days

36°F threshold

	10%	50%	90%
Last, on or after	March 2	February 1	January 1
First, on or before	November 25	December 11	December 29
Season at least	347 days	314 days	279 days

Station PHOENIX DEER VALLEY MUNI AP, AZ US (USW00003184). Completeness flag R, 21 years used for the 32°F dates. NCEI’s annual probability of at least one day at or below 32°F is 70.2%. Freeze dates are conditional on that threshold occurring. Elevation 443.5 m. The same probability language applies to the 28°F and 36°F rows when those dates passed the same quality checks.

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Phoenix, AZ

Zone 9bAverage annual extreme minimum 25°F to 30°F

Outside the median season Growing seasonTicks: 10%, 50%, and 90%

Arizona. Nearest qualified station: PHOENIX DEER VALLEY MUNI AP, AZ US (USW00003184), 8 miles. Median last 32°F January 8. Median first 32°F December 25. The 50% growing-season length is 354 days.

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32°F probabilities at this station

	10%	50%	90%
Last 32°F on or after	February 12	January 8	December 16
First 32°F on or before	December 5	December 25	January 23

Column order matches the NCEI file: for the last freeze, 10% is the later date and 90% is the earlier date. How to read the probabilities.

A wall calendar surrounded by vegetables, herbs, seed packets, and watering cans.

Planting calendar

Frost dates for Arizona are above. Planting windows appear for states with a cited extension guide. The fall and seed tools use the numbers you enter and the station dates.

Date checks use your device’s calendar and appear after the page loads.