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USDA Hardiness Zone 9b

Frost Dates for 85712 — Tucson, Arizona

NOAA 1991–2020 normals from Tucson Camp Ave Exp, AZ (2,330 ft), 4 miles northwest.

Updated

In Tucson, the last spring frost (32°F) is around February 20 in half of years and has passed by March 11 in nine years out of ten. The first fall frost comes around November 27, as early as November 10 one year in ten, leaving a typical freeze-free season of 280 days (NOAA, Tucson Camp Ave Exp, AZ).

Last spring frost
February 20

50% probability

First fall frost
November 27

50% probability

Growing season
280 days

freeze-free, 50%

Hardiness zone
9b

25 to 30°F (-3.9 to -1.1°C) coldest night

First snow
Rare

median, 1991–2020

Last snow
Rare

median, 1991–2020

Winters with snow
0%

0 of 20 observed

Snow per year
0"

NOAA normal

Frost risk by date in Tucson

Half of springs at Tucson Camp Ave Exp, AZ see their last 32°F night by February 20; only one in ten is past it by January 30, and one in ten still has one after March 11. Planting tender crops after March 1 leaves a 30% risk of a frost on them, after March 5 20%, and after March 11 10%. The 19 days between the even-odds date and the one-in-ten date is narrower than at 61% of the 98 Arizona stations behind this site's ZIP pages.

In fall the first 32°F night comes by November 27 in half of years, as early as November 10 one year in ten, and holds off past December 12 one year in ten. A hard freeze of 28°F follows 13 days later, around December 10; in spring the one-in-ten date for 28°F is February 24, 15 days before the 32°F one. The freeze-free season lasts 280 days in a typical year, longer than at 65% of the 98 Arizona stations; it reaches 308 days one year in ten and falls short of 253 one year in ten. On average 26 nights a year drop to 32°F or below. Nights of 36°F, when frost can still settle on leaves in low, open spots, continue 20 days longer, to about March 12, and return around November 16. Nights of 24°F, cold enough to damage hardier plants, come in 63% of winters and 16°F in 0%.

Spring: the chance of another night this cold after the date
Low90%80%70%60%50%40%30%20%10%
36°FFeb 19Feb 28Mar 4Mar 8Mar 12Mar 16Mar 21Mar 28Apr 5
32°FJan 30Feb 6Feb 11Feb 16Feb 20Feb 25Mar 1Mar 5Mar 11
28°F98% of yrsDec 29Jan 7Jan 15Jan 23Jan 30Feb 4Feb 9Feb 15Feb 24
24°F63% of yrsDec 9Dec 19Dec 26Dec 31Jan 8Jan 15Jan 22Jan 31Feb 6
20°F11% of yrstoo rare for a date
16°F0% of yrstoo rare for a date
Fall: the chance the first night this cold has come by the date
Low10%20%30%40%50%60%70%80%90%
36°FNov 1Nov 6Nov 9Nov 13Nov 16Nov 19Nov 22Nov 25Dec 1
32°FNov 10Nov 16Nov 20Nov 24Nov 27Nov 30Dec 3Dec 7Dec 12
28°F98% of yrsNov 23Nov 28Dec 2Dec 6Dec 10Dec 14Dec 20Dec 25Jan 2
24°F63% of yrsDec 1Dec 9Dec 15Dec 20Dec 25Dec 30Jan 3Jan 12Jan 26
20°F11% of yrstoo rare for a date
16°F0% of yrstoo rare for a date

Freeze probabilities 1991–2020 at Tucson Camp Ave Exp, AZ, from NOAA NCEI U.S. Climate Normals. Where a temperature is reached in fewer than 99.5% of years, the dates describe only the years that reach it. Not a forecast.

Frost risk on any date in 85712 →Compare Tucson with another place →

Weather by month in Tucson

July is the warmest month at Tucson Camp Ave Exp, AZ, averaging 101°F by day and 75°F at night; December is the coldest at 67°F and 36°F. A freezing night is all but certain in every month from December to January (a 90% chance or more). From April to October the chance of a 32°F night stays under 10% each month. In spring, February still brings one in 81% of years and March still brings one in 30% of years.

Warmth for growing adds up to 7,312 growing degree days a year (base 50°F), more than at 64% of the 102 Arizona stations. 41% of them (2,963) have built up by the end of June, and July adds the most, 1,173. Precipitation totals 11.7 inches a year, most in August (2.6") and least in May (0.1"); May to September bring 54% of it.

Monthly normals 1991–2020 at Tucson Camp Ave Exp, AZ
MonthHigh °FLow °FPrecip. in32°F nightNights ≤ 32°FGDD 50°F
Jan68371.197%9115
Feb71401.081%4166
Mar78450.630%1347
Apr85500.31%0516
May93580.10%0780
Jun102680.30%01039
Jul101752.30%01173
Aug100742.60%01136
Sep96681.00%0963
Oct88550.61%0662
Nov77430.760%2311
Dec67361.199%11104

Monthly normals 1991–2020 at Tucson Camp Ave Exp, AZ (2,330 ft), NOAA NCEI. "32°F night": chance of at least one in the month. GDD: growing degree days, base 50°F.

Compared with the next station

The nearest other station, Tucson WFO, AZ, 4 miles west of Tucson, has a last frost 31 days earlier (January 20), a first frost 20 days later (December 17), a season 52 days longer.

Frost dates for 85719 (Tucson) →

When it snows in Tucson, Arizona

Measurable snow is rare here: only 0 of 20 winters from 1991 to 2020 recorded 0.1 inch or more at Tucson Camp Ave Exp, AZ, 4 miles away, so there is no typical first-snow date to plan around.

Planting calendar for 85712

What to do and when, from the 50% frost dates for Tucson, Arizona
WhenWhat to do
December 12 – December 26Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out.
December 26 – January 9Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early.
January 23 – February 6Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil.
February 20 onwardTransplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast.
by September 4Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops.
by November 13Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation.
November 27 onwardPlant garlic, mulch beds, lift tender bulbsGarlic wants a cold spell; bare soil loses structure over winter.

The weeks before and after the 50% dates are general rules of thumb, not NOAA figures; a seed packet gives the timing for each variety.

Where these figures come from

ZIP 85712 is 4 miles from Tucson Camp Ave Exp, AZ, which stands at 2,330 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 2 other ZIP codes share the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 85712 in zone 9b, the band where the coldest night of the year averaged 25 to 30°F (-3.9 to -1.1°C) over 1991–2020; a zone describes winter lows, not frost dates.

Frost dates across Arizona →

Hardiness zone and temperature range: USDA Plant Hardiness Zone Map 2023 (USDA-ARS, Oregon State University), ZIP-code listing, unchanged. °C converted from °F by this site.

Thirty-year averages, not a forecast: check the forecast before planting out. How stations are matched and which pages are offered to search engines: methodology.

ZIP codes measured at the same station

Other zone 9b places in Arizona