Frost dates / Arizona / Tucson

Frost dates in Tucson, AZ

The station on this page is TUCSON INTL AP, AZ US (USW00023160), 5.2 miles from the city point. Population in the Census 2024 estimate is 554,013.

Zone 9bUSDA average annual extreme minimum 25°F to 30°F, from ZIP 85708 (1.7 miles from the city point used on this page).

Median last 32°F is February 5. Median first 32°F is December 9. The 50% growing-season length is 307 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%	January 4	Earlier date. A last 32°F on or after this day is common.
50%	February 5	Median.
10%	March 2	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%	November 21	Earlier date. A first 32°F on or before this day is uncommon.
50%	December 9	Median.
90%	January 3	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%	344
50%	307
90%	274

28°F threshold

	10%	50%	90%
Last, on or after	February 17	January 11	December 14
First, on or before	November 30	December 26	February 1
Season at least	365 days	351 days	314 days

36°F threshold

	10%	50%	90%
Last, on or after	March 24	February 28	February 3
First, on or before	November 11	November 26	December 14
Season at least	301 days	271 days	241 days

Station TUCSON INTL AP, AZ US (USW00023160). Completeness flag S, 29 years used for the 32°F dates. NCEI’s annual probability of at least one day at or below 32°F is 98.9%. Freeze dates are conditional on that threshold occurring. Elevation 776.9 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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Tucson, 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: TUCSON INTL AP, AZ US (USW00023160), 5.2 miles. Median last 32°F February 5. Median first 32°F December 9. The 50% growing-season length is 307 days.

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32°F probabilities at this station

	10%	50%	90%
Last 32°F on or after	March 2	February 5	January 4
First 32°F on or before	November 21	December 9	January 3

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.

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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.