USDA Hardiness Zone 9b
Frost Dates for 85361 — Wittmann, Arizona
NOAA 1991–2020 normals from Wittmann 1SE, AZ (1,683 ft), 5 miles northeast.
Updated
In Wittmann, the last spring frost (32°F) is around February 5 in half of years and has passed by March 3 in nine years out of ten. The first fall frost comes around December 11, as early as November 20 one year in ten, leaving a typical freeze-free season of 306 days (NOAA, Wittmann 1SE, AZ).
- Last spring frost
- February 5
- First fall frost
- December 11
- Growing season
- 306 days
- Hardiness zone
- 9b
50% probability
50% probability
freeze-free, 50%
25 to 30°F (-3.9 to -1.1°C) coldest night
- First snow
- Rare
- Last snow
- Rare
- Winters with snow
- 5%
- Snow per year
- 0.1"
median, 1991–2020
median, 1991–2020
1 of 22 observed
NOAA normal
Frost risk by date in Wittmann
Half of springs at Wittmann 1SE, AZ see their last 32°F night by February 5; only one in ten is past it by January 6, and one in ten still has one after March 3. Planting tender crops after February 16 leaves a 30% risk of a frost on them, after February 24 20%, and after March 3 10%. The 26 days between the even-odds date and the one-in-ten date is wider than at 67% of the 98 Arizona stations behind this site's ZIP pages, so a fixed calendar date is a gamble here.
In fall the first 32°F night comes by December 11 in half of years, as early as November 20 one year in ten, and holds off past January 2 one year in ten. A hard freeze of 28°F follows 16 days later, around December 27; in spring the one-in-ten date for 28°F is February 12, 19 days before the 32°F one. The freeze-free season lasts 306 days in a typical year, longer than at 73% of the 98 Arizona stations; it reaches 341 days one year in ten and falls short of 270 one year in ten. On average 13 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 27 days longer, to about March 4, and return around November 26. A 24°F night is unusual: 23% of winters had one.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Feb 6 | Feb 15 | Feb 21 | Feb 28 | Mar 4 | Mar 9 | Mar 14 | Mar 21 | Apr 2 |
| 32°F99% of yrs | Jan 6 | Jan 16 | Jan 24 | Jan 31 | Feb 5 | Feb 11 | Feb 16 | Feb 24 | Mar 3 |
| 28°F76% of yrs | Dec 14 | Dec 27 | Jan 3 | Jan 9 | Jan 15 | Jan 22 | Jan 30 | Feb 5 | Feb 12 |
| 24°F23% of yrs | too rare for a date | ||||||||
| 20°F2% of yrs | too rare for a date | ||||||||
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Nov 8 | Nov 16 | Nov 20 | Nov 24 | Nov 26 | Dec 1 | Dec 5 | Dec 9 | Dec 14 |
| 32°F99% of yrs | Nov 20 | Nov 26 | Dec 2 | Dec 7 | Dec 11 | Dec 15 | Dec 19 | Dec 25 | Jan 2 |
| 28°F76% of yrs | Dec 4 | Dec 12 | Dec 17 | Dec 23 | Dec 27 | Dec 30 | Jan 5 | Jan 14 | Jan 28 |
| 24°F23% of yrs | too rare for a date | ||||||||
| 20°F2% of yrs | too rare for a date | ||||||||
Freeze probabilities 1991–2020 at Wittmann 1SE, 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 85361 →Compare Wittmann with another place →
Weather by month in Wittmann
July is the warmest month at Wittmann 1SE, AZ, averaging 105°F by day and 77°F at night; December is the coldest at 64°F and 39°F. From April to October the chance of a 32°F night stays under 10% each month. In spring, February still brings one in 53% of years and March still brings one in 13% of years.
Warmth for growing adds up to 7,546 growing degree days a year (base 50°F), more than at 70% of the 102 Arizona stations. 39% of them (2,949) have built up by the end of June, and July adds the most, 1,262. Precipitation totals 9.9 inches a year, most in February (1.5") and least in May (0.1"); May to September bring 33% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 65 | 39 | 1.4 | 84% | 4 | 113 |
| Feb | 68 | 41 | 1.5 | 53% | 3 | 158 |
| Mar | 75 | 46 | 1.0 | 13% | <1 | 323 |
| Apr | 82 | 51 | 0.3 | 0% | 0 | 491 |
| May | 92 | 60 | 0.1 | 0% | 0 | 801 |
| Jun | 102 | 69 | 0.1 | 0% | 0 | 1063 |
| Jul | 105 | 77 | 0.9 | 0% | 0 | 1262 |
| Aug | 103 | 77 | 1.1 | 0% | 0 | 1243 |
| Sep | 98 | 70 | 1.1 | 0% | 0 | 1011 |
| Oct | 87 | 57 | 0.7 | 1% | <1 | 676 |
| Nov | 74 | 46 | 0.7 | 26% | 1 | 306 |
| Dec | 64 | 39 | 1.0 | 84% | 5 | 100 |
Monthly normals 1991–2020 at Wittmann 1SE, AZ (1,683 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, Wickenburg, AZ, 18 miles northwest of Wittmann and 412 feet higher, has a last frost 30 days later (March 7), a first frost 21 days earlier (November 20), a season 52 days shorter.
When it snows in Wittmann, Arizona
Measurable snow is rare here: only 1 of 22 winters from 1991 to 2020 recorded 0.1 inch or more at Wickenburg, AZ, 18.4 miles away, so there is no typical first-snow date to plan around.
Planting calendar for 85361
| When | What to do |
|---|---|
| November 27 – December 11 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| December 11 – December 25 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| January 8 – January 22 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| February 5 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by September 18 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by November 27 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| December 11 onward | Plant 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 85361 is 5 miles from Wittmann 1SE, AZ, which stands at 1,683 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 85361 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.
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.