USDA Hardiness Zone 10a
Frost Dates for 85027 — Phoenix, Arizona
NOAA 1991–2020 normals from Phoenix Deer Valley Municipal Airport, AZ (1,455 ft), 2 miles east.
Updated
A freeze (32°F) reaches Phoenix in 70% of winters. When it does, the first fall frost comes around December 25 and the last spring frost around January 8; after February 12 the chance of another is under 7%.
- Last spring frost
- January 8
- First fall frost
- December 25
- Winters with a freeze
- 70%
- Hardiness zone
- 10a
50%, in freezing years
50%, in freezing years
32°F or below, 1991–2020
30 to 35°F (-1.1 to 1.7°C) coldest night
- First snow
- Rare
- Last snow
- Rare
- Winters with snow
- 0%
- Snow per year
- 0"
median, 1991–2020
median, 1991–2020
0 of 25 observed
NOAA normal
Frost risk by date in Phoenix
In the 70% of winters that bring a 32°F night, half of springs at Phoenix Deer Valley Municipal Airport, AZ see their last 32°F night by January 8; only one in ten is past it by December 16, and one in ten still has one after February 12. Counting the winters with no freeze at all, the risk of a 32°F night after February 12 is under 7% and after January 8 35%. The 35 days between the even-odds date and the one-in-ten date is wider than at 94% 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 25 in half of years, as early as December 5 one year in ten, and holds off past January 23 one year in ten. A hard freeze of 28°F is less common: it came in 17% of winters. The freeze-free season lasts 354 days in a typical year, longer than at 96% of the 98 Arizona stations; it reaches 365 days one year in ten and falls short of 320 one year in ten. On average 3 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 24 days longer, to about February 1, and return around December 11. A 24°F night is unusual: 2% of winters had one.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F99% of yrs | Jan 1 | Jan 10 | Jan 17 | Jan 24 | Feb 1 | Feb 7 | Feb 13 | Feb 21 | Mar 2 |
| 32°F70% of yrs | Dec 16 | Dec 24 | Dec 31 | Jan 2 | Jan 8 | Jan 14 | Jan 23 | Feb 1 | Feb 12 |
| 28°F17% of yrs | too rare for a date | ||||||||
| 24°F2% of yrs | too rare for a date | ||||||||
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F99% of yrs | Nov 25 | Dec 1 | Dec 5 | Dec 8 | Dec 11 | Dec 15 | Dec 18 | Dec 23 | Dec 29 |
| 32°F70% of yrs | Dec 5 | Dec 11 | Dec 15 | Dec 20 | Dec 25 | Dec 29 | Jan 2 | Jan 9 | Jan 23 |
| 28°F17% of yrs | too rare for a date | ||||||||
| 24°F2% of yrs | too rare for a date | ||||||||
Freeze probabilities 1991–2020 at Phoenix Deer Valley Municipal Airport, 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 85027 →Compare Phoenix with another place →
Weather by month in Phoenix
July is the warmest month at Phoenix Deer Valley Municipal Airport, AZ, averaging 104°F by day and 81°F at night; December is the coldest at 64°F and 43°F. From March to November the chance of a 32°F night stays under 10% each month. In spring, February still brings one in 14% of years.
Warmth for growing adds up to 8,306 growing degree days a year (base 50°F), more than at 85% of the 102 Arizona stations. 40% of them (3,355) have built up by the end of June, and July adds the most, 1,314. Precipitation totals 9.0 inches a year, most in January (1.2") and least in June (0.0"); May to September bring 30% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 65 | 44 | 1.2 | 39% | 1 | 171 |
| Feb | 68 | 46 | 1.2 | 14% | <1 | 210 |
| Mar | 75 | 51 | 1.1 | 1% | <1 | 403 |
| Apr | 83 | 57 | 0.4 | 0% | 0 | 587 |
| May | 92 | 65 | 0.2 | 0% | 0 | 871 |
| Jun | 102 | 73 | 0.0 | 0% | 0 | 1113 |
| Jul | 104 | 81 | 0.8 | 0% | 0 | 1314 |
| Aug | 103 | 81 | 1.0 | 0% | 0 | 1286 |
| Sep | 98 | 75 | 0.7 | 0% | 0 | 1083 |
| Oct | 86 | 63 | 0.7 | 0% | 0 | 760 |
| Nov | 74 | 51 | 0.9 | 4% | <1 | 375 |
| Dec | 64 | 43 | 0.8 | 44% | 1 | 133 |
Monthly normals 1991–2020 at Phoenix Deer Valley Municipal Airport, AZ (1,455 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, Scottsdale Municipal Airport, AZ, 13 miles southeast of Phoenix, has a last frost 2 days earlier (January 6), a first frost 1 day later (December 26), a season 1 day shorter.
When it snows in Phoenix, Arizona
Measurable snow is rare here: only 0 of 25 winters from 1991 to 2020 recorded 0.1 inch or more at Youngtown, AZ, 12.9 miles away, so there is no typical first-snow date to plan around.
Where these figures come from
ZIP 85027 is 2 miles from Phoenix Deer Valley Municipal Airport, AZ, which stands at 1,455 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 14 other ZIP codes share the station; its figures are presented in full for 85308 (Glendale). The 2023 USDA Plant Hardiness Zone Map lists ZIP 85027 in zone 10a, the band where the coldest night of the year averaged 30 to 35°F (-1.1 to 1.7°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.