USDA Hardiness Zone 9b
Frost Dates for 85086 — Anthem, Arizona
NOAA 1991–2020 normals from Carefree, AZ (2,530 ft), 9 miles east.
Updated
In Anthem, the last spring frost (32°F) is around February 4 in half of years and has passed by March 9 in nine years out of ten. The first fall frost comes around December 16, as early as November 24 one year in ten, leaving a typical freeze-free season of 313 days (NOAA, Carefree, AZ).
- Last spring frost
- February 4
- First fall frost
- December 16
- Growing season
- 313 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
- 17%
- Snow per year
- 0"
median, 1991–2020
median, 1991–2020
4 of 24 observed
NOAA normal
Frost risk by date in Anthem
Half of springs at Carefree, AZ see their last 32°F night by February 4; only one in ten is past it by January 3, and one in ten still has one after March 9. Planting tender crops after February 20 leaves a 30% risk of a frost on them, after March 1 20%, and after March 9 10%. The 33 days between the even-odds date and the one-in-ten date is wider than at 90% 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 16 in half of years, as early as November 24 one year in ten, and holds off past January 15 one year in ten. A hard freeze of 28°F follows 16 days later, around January 1; in spring the one-in-ten date for 28°F is February 22, 15 days before the 32°F one. The freeze-free season lasts 313 days in a typical year, longer than at 79% of the 98 Arizona stations; it reaches 351 days one year in ten and falls short of 273 one year in ten. On average 6 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 29 days longer, to about March 5, and return around December 1. A 24°F night is unusual: 15% of winters had one.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Jan 31 | Feb 12 | Feb 20 | Feb 27 | Mar 5 | Mar 10 | Mar 15 | Mar 24 | Apr 2 |
| 32°F98% of yrs | Jan 3 | Jan 11 | Jan 20 | Jan 30 | Feb 4 | Feb 13 | Feb 20 | Mar 1 | Mar 9 |
| 28°F60% of yrs | Dec 19 | Dec 29 | Jan 3 | Jan 8 | Jan 14 | Jan 24 | Jan 31 | Feb 10 | Feb 22 |
| 24°F15% of yrs | too rare for a date | ||||||||
| 20°F0% of yrs | too rare for a date | ||||||||
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Nov 13 | Nov 19 | Nov 23 | Nov 27 | Dec 1 | Dec 4 | Dec 8 | Dec 12 | Dec 18 |
| 32°F98% of yrs | Nov 24 | Dec 1 | Dec 6 | Dec 12 | Dec 16 | Dec 20 | Dec 25 | Jan 1 | Jan 15 |
| 28°F60% of yrs | Dec 5 | Dec 15 | Dec 24 | Dec 29 | Jan 1 | Jan 6 | Jan 13 | Jan 26 | Feb 9 |
| 24°F15% of yrs | too rare for a date | ||||||||
| 20°F0% of yrs | too rare for a date | ||||||||
Freeze probabilities 1991–2020 at Carefree, 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 85086 →Compare Anthem with another place →
Weather by month in Anthem
July is the warmest month at Carefree, AZ, averaging 103°F by day and 76°F at night; December is the coldest at 64°F and 41°F. From April to October the chance of a 32°F night stays under 10% each month. In spring, February still brings one in 42% of years and March still brings one in 18% of years.
Warmth for growing adds up to 7,680 growing degree days a year (base 50°F), more than at 72% of the 102 Arizona stations. 40% of them (3,049) have built up by the end of June, and July adds the most, 1,229. Precipitation totals 12.7 inches a year, most in January (1.8") and least in June (0.1"); May to September bring 32% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 65 | 42 | 1.8 | 74% | 2 | 134 |
| Feb | 68 | 44 | 1.6 | 42% | 1 | 180 |
| Mar | 74 | 48 | 1.6 | 18% | <1 | 349 |
| Apr | 82 | 53 | 0.5 | 2% | 0 | 517 |
| May | 91 | 61 | 0.2 | 0% | 0 | 809 |
| Jun | 101 | 70 | 0.1 | 0% | 0 | 1060 |
| Jul | 103 | 76 | 1.3 | 0% | 0 | 1229 |
| Aug | 102 | 76 | 1.3 | 0% | 0 | 1212 |
| Sep | 97 | 70 | 1.2 | 0% | 0 | 1011 |
| Oct | 86 | 60 | 1.0 | 0% | 0 | 707 |
| Nov | 74 | 49 | 0.8 | 19% | <1 | 351 |
| Dec | 64 | 41 | 1.3 | 73% | 3 | 121 |
Monthly normals 1991–2020 at Carefree, AZ (2,530 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, Phoenix Deer Valley Municipal Airport, AZ, 10 miles south of Anthem and 1,075 feet lower, has a last frost 27 days earlier (January 8), a first frost 9 days later (December 25), a season 41 days longer.
When it snows in Anthem, Arizona
Measurable snow is rare here: only 4 of 24 winters from 1991 to 2020 recorded 0.1 inch or more at Carefree, AZ, 9.3 miles away, so there is no typical first-snow date to plan around.
Planting calendar for 85086
| When | What to do |
|---|---|
| November 26 – December 10 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| December 10 – December 24 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| January 7 – January 21 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| February 4 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by September 23 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by December 2 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| December 16 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 85086 is 9 miles from Carefree, AZ, which stands at 2,530 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 4 other ZIP codes share the station; its figures are presented in full for 85286 (Chandler). The 2023 USDA Plant Hardiness Zone Map lists ZIP 85086 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.