USDA Hardiness Zone 9b
Frost Dates for 85032 — Phoenix, Arizona
NOAA 1991–2020 normals from Scottsdale Municipal Airport, AZ (1,473 ft), 5 miles east.
Updated
A freeze (32°F) reaches Phoenix in 70% of winters. When it does, the first fall frost comes around December 26 and the last spring frost around January 6; after February 7 the chance of another is under 7%.
- Last spring frost
- January 6
- First fall frost
- December 26
- Winters with a freeze
- 70%
- 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
- 0%
- Snow per year
- 0"
median, 1991–2020
median, 1991–2020
0 of 30 observed
NOAA normal
Frost risk by date in Phoenix
In the 70% of winters that bring a 32°F night, half of springs at Scottsdale Municipal Airport, AZ see their last 32°F night by January 6; only one in ten is past it by December 16, and one in ten still has one after February 7. Counting the winters with no freeze at all, the risk of a 32°F night after February 7 is under 7% and after January 6 35%. The 32 days between the even-odds date and the one-in-ten date is wider than at 87% 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 26 in half of years, as early as December 4 one year in ten, and holds off past January 20 one year in ten. A hard freeze of 28°F is less common: it came in 13% of winters. The freeze-free season lasts 353 days in a typical year, longer than at 95% of the 98 Arizona stations; it reaches 365 days one year in ten and falls short of 322 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 January 30, and return around December 11. A 24°F night is unusual: 0% of winters had one.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F99% of yrs | Jan 3 | Jan 11 | Jan 17 | Jan 23 | Jan 30 | Feb 3 | Feb 10 | Feb 16 | Feb 26 |
| 32°F70% of yrs | Dec 16 | Dec 25 | Dec 30 | Jan 2 | Jan 6 | Jan 12 | Jan 18 | Jan 26 | Feb 7 |
| 28°F13% of yrs | too rare for a date | ||||||||
| 24°F0% of yrs | too rare for a date | ||||||||
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F99% of yrs | Nov 25 | Nov 30 | Dec 4 | Dec 8 | Dec 11 | Dec 14 | Dec 18 | Dec 23 | Dec 30 |
| 32°F70% of yrs | Dec 4 | Dec 11 | Dec 17 | Dec 22 | Dec 26 | Dec 29 | Jan 1 | Jan 7 | Jan 20 |
| 28°F13% of yrs | too rare for a date | ||||||||
| 24°F0% of yrs | too rare for a date | ||||||||
Freeze probabilities 1991–2020 at Scottsdale 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 85032 →Compare Phoenix with another place →
Weather by month in Phoenix
July is the warmest month at Scottsdale Municipal Airport, AZ, averaging 104°F by day and 83°F at night; December is the coldest at 65°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 10% of years.
Warmth for growing adds up to 8,567 growing degree days a year (base 50°F), more than at 87% of the 102 Arizona stations. 41% of them (3,512) have built up by the end of June, and July adds the most, 1,344. Precipitation totals 8.7 inches a year, most in February (1.2") and least in June (0.1"); May to September bring 30% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 67 | 43 | 1.1 | 39% | 1 | 173 |
| Feb | 69 | 46 | 1.2 | 10% | <1 | 216 |
| Mar | 76 | 52 | 1.1 | 0% | 0 | 426 |
| Apr | 83 | 58 | 0.3 | 0% | 0 | 617 |
| May | 92 | 67 | 0.2 | 0% | 0 | 907 |
| Jun | 102 | 76 | 0.1 | 0% | 0 | 1173 |
| Jul | 104 | 83 | 0.9 | 0% | 0 | 1344 |
| Aug | 103 | 82 | 0.8 | 0% | 0 | 1313 |
| Sep | 98 | 75 | 0.6 | 0% | 0 | 1102 |
| Oct | 87 | 63 | 0.6 | 0% | 0 | 775 |
| Nov | 75 | 51 | 0.8 | 5% | <1 | 383 |
| Dec | 65 | 43 | 1.0 | 45% | 1 | 137 |
Monthly normals 1991–2020 at Scottsdale Municipal Airport, AZ (1,473 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, 6 miles northwest of Phoenix, has a last frost 2 days later (January 8), a first frost 1 day earlier (December 25), a season 1 day longer.
When it snows in Phoenix, Arizona
Measurable snow is rare here: only 0 of 30 winters from 1991 to 2020 recorded 0.1 inch or more at Tempe Asu, AZ, 14.5 miles away, so there is no typical first-snow date to plan around.
Where these figures come from
ZIP 85032 is 5 miles from Scottsdale Municipal Airport, AZ, which stands at 1,473 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 7 other ZIP codes share the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 85032 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.