USDA Hardiness Zone 9b
Frost Dates for 85043 — Phoenix, Arizona
NOAA 1991–2020 normals from Laveen 3 SSE, AZ (1,135 ft), 7 miles southeast.
Updated
A freeze (32°F) reaches Phoenix in 85% of winters. When it does, the first fall frost comes around December 22 and the last spring frost around January 14; after February 12 the chance of another is under 8%.
- Last spring frost
- January 14
- First fall frost
- December 22
- Winters with a freeze
- 85%
- Hardiness zone
- 9b
50%, in freezing years
50%, in freezing years
32°F or below, 1991–2020
25 to 30°F (-3.9 to -1.1°C) coldest night
- First snow
- Rare
- Last snow
- Rare
- Winters with snow
- 26%
- Snow per year
- 0.2"
median, 1991–2020
median, 1991–2020
5 of 19 observed
NOAA normal
Frost risk by date in Phoenix
In the 85% of winters that bring a 32°F night, half of springs at Laveen 3 SSE, AZ see their last 32°F night by January 14; only one in ten is past it by December 19, 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 8% and after January 14 42%. The 29 days between the even-odds date and the one-in-ten date is wider than at 79% 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 22 in half of years, as early as December 1 one year in ten, and holds off past January 22 one year in ten. A hard freeze of 28°F is less common: it came in 25% of winters. The freeze-free season lasts 343 days in a typical year, longer than at 91% of the 98 Arizona stations; it reaches 365 days one year in ten and falls short of 310 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 23 days longer, to about February 6, and return around December 8. A 24°F night is unusual: 2% of winters had one.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Jan 8 | Jan 20 | Jan 28 | Feb 2 | Feb 6 | Feb 11 | Feb 17 | Feb 23 | Mar 1 |
| 32°F85% of yrs | Dec 19 | Dec 29 | Jan 3 | Jan 8 | Jan 14 | Jan 21 | Jan 29 | Feb 4 | Feb 12 |
| 28°F25% 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°F | Nov 22 | Nov 27 | Dec 1 | Dec 4 | Dec 8 | Dec 11 | Dec 15 | Dec 19 | Dec 24 |
| 32°F85% of yrs | Dec 1 | Dec 7 | Dec 12 | Dec 17 | Dec 22 | Dec 27 | Dec 31 | Jan 7 | Jan 22 |
| 28°F25% of yrs | too rare for a date | ||||||||
| 24°F2% of yrs | too rare for a date | ||||||||
Freeze probabilities 1991–2020 at Laveen 3 SSE, 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 85043 →Compare Phoenix with another place →
Weather by month in Phoenix
July is the warmest month at Laveen 3 SSE, AZ, averaging 107°F by day and 81°F at night; December is the coldest at 66°F and 42°F. From March to November the chance of a 32°F night stays under 10% each month. In spring, February still brings one in 22% of years.
Warmth for growing adds up to 8,822 growing degree days a year (base 50°F), more than at 91% of the 102 Arizona stations. 42% of them (3,662) have built up by the end of June, and July adds the most, 1,376. Precipitation totals 7.4 inches a year, most in July (1.0") and least in May (0.1"); May to September bring 35% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 67 | 43 | 0.8 | 53% | 2 | 169 |
| Feb | 71 | 46 | 0.9 | 22% | <1 | 233 |
| Mar | 79 | 51 | 0.9 | 0% | 0 | 450 |
| Apr | 87 | 56 | 0.2 | 0% | 0 | 648 |
| May | 96 | 66 | 0.1 | 0% | 0 | 955 |
| Jun | 106 | 75 | 0.1 | 0% | 0 | 1207 |
| Jul | 107 | 81 | 1.0 | 0% | 0 | 1376 |
| Aug | 106 | 81 | 0.8 | 0% | 0 | 1344 |
| Sep | 101 | 74 | 0.6 | 0% | 0 | 1124 |
| Oct | 89 | 61 | 0.7 | 0% | 0 | 780 |
| Nov | 76 | 50 | 0.6 | 8% | 1 | 393 |
| Dec | 66 | 42 | 0.7 | 55% | 3 | 144 |
Monthly normals 1991–2020 at Laveen 3 SSE, AZ (1,135 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, South Phoenix, AZ, 8 miles southeast of Phoenix, has a last frost 7 days later (January 21), a first frost 6 days earlier (December 16), a season 12 days shorter.
When it snows in Phoenix, Arizona
Measurable snow is rare here: only 5 of 19 winters from 1991 to 2020 recorded 0.1 inch or more at Tolleson 1 E, AZ, 2.7 miles away, so there is no typical first-snow date to plan around.
Where these figures come from
ZIP 85043 is 7 miles from Laveen 3 SSE, AZ, which stands at 1,135 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 6 other ZIP codes share the station; its figures are presented in full for 85339 (Laveen). The 2023 USDA Plant Hardiness Zone Map lists ZIP 85043 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.