Frost dates / Arizona / Casa Grande

Frost dates in Casa Grande, AZ

The station on this page is CASA GRANDE, AZ US (USC00021306), 3.1 miles from the city point. Population in the Census 2024 estimate is 68,927.

Zone 9aUSDA average annual extreme minimum 20°F to 25°F, from ZIP 85122 (1.1 miles from the city point used on this page).

Median last 32°F is February 5. Median first 32°F is December 6. The 50% growing-season length is 305 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 5	Earlier date. A last 32°F on or after this day is common.
50%	February 5	Median.
10%	February 28	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 18	Earlier date. A first 32°F on or before this day is uncommon.
50%	December 6	Median.
90%	December 29	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%	340
50%	305
90%	273

28°F threshold

	10%	50%	90%
Last, on or after	February 15	January 14	December 16
First, on or before	November 29	December 22	January 24
Season at least	365 days	340 days	304 days

36°F threshold

	10%	50%	90%
Last, on or after	March 16	February 26	January 31
First, on or before	November 7	November 24	December 11
Season at least	299 days	271 days	243 days

Station CASA GRANDE, AZ US (USC00021306). Completeness flag R, 18 years used for the 32°F dates. NCEI’s annual probability of at least one day at or below 32°F is 98.6%. Freeze dates are conditional on that threshold occurring. Elevation 426.7 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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Casa Grande, AZ

Zone 9aAverage annual extreme minimum 20°F to 25°F

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

Arizona. Nearest qualified station: CASA GRANDE, AZ US (USC00021306), 3.1 miles. Median last 32°F February 5. Median first 32°F December 6. The 50% growing-season length is 305 days.

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32°F probabilities at this station

	10%	50%	90%
Last 32°F on or after	February 28	February 5	January 5
First 32°F on or before	November 18	December 6	December 29

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.

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