USDA Hardiness Zone 9b
Frost Dates for 85015 — Phoenix, Arizona
NOAA 1991–2020 normals from Phoenix Sky Harbor International Airport, AZ (1,107 ft), 8 miles southeast.
Updated
Frost is not a yearly event in Phoenix: a night at or below 32°F came in 18% of the winters of 1991–2020 at Phoenix Sky Harbor International Airport, AZ, and a 36°F night, cold enough for frost on exposed leaves, in 78%. There is no reliable "last frost date" here; most years have none.
- Winters with a freeze
- 18%
- Winters with 36°F
- 78%
- Coldest month low
- 45°F
- Hardiness zone
- 9b
32°F or below, 1991–2020
frost possible on leaves
average, December
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 17 observed
NOAA normal
Frost risk by date in Phoenix
At Phoenix Sky Harbor International Airport, AZ, 8 miles southeast of Phoenix, 18% of the winters of 1991–2020 had at least one night at or below 32°F, 1% reached 28°F. Nights of 36°F, enough for frost on exposed leaves, are more common (78% of winters) and, when they come, fall between about December 24 and January 6. January is the month most likely to bring one: a 11% chance in a given year. 3 of the 102 other Arizona stations behind this site's ZIP pages freeze in fewer than half of winters too.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F78% of yrs | Dec 14 | Dec 24 | Dec 30 | Jan 2 | Jan 6 | Jan 11 | Jan 18 | Jan 26 | Feb 6 |
| 32°F18% of yrs | too rare for a date | ||||||||
| 28°F1% of yrs | too rare for a date | ||||||||
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F78% of yrs | Dec 5 | Dec 11 | Dec 14 | Dec 20 | Dec 24 | Dec 28 | Jan 1 | Jan 5 | Jan 16 |
| 32°F18% of yrs | too rare for a date | ||||||||
| 28°F1% of yrs | too rare for a date | ||||||||
Freeze probabilities 1991–2020 at Phoenix Sky Harbor International 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 85015 →Compare Phoenix with another place →
Weather by month in Phoenix
July is the warmest month at Phoenix Sky Harbor International Airport, AZ, averaging 107°F by day and 85°F at night; December is the coldest at 66°F and 45°F. From February to December the chance of a 32°F night stays under 10% each month.
Warmth for growing adds up to 9,390 growing degree days a year (base 50°F), more than at 98% of the 102 Arizona stations. 42% of them (3,934) have built up by the end of June, and July adds the most, 1,411. Precipitation totals 7.2 inches a year, most in January (0.9") and least in June (0.0"); May to September bring 35% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 68 | 46 | 0.9 | 11% | <1 | 220 |
| Feb | 71 | 49 | 0.9 | 1% | <1 | 280 |
| Mar | 78 | 55 | 0.8 | 0% | 0 | 506 |
| Apr | 86 | 61 | 0.2 | 0% | 0 | 695 |
| May | 95 | 70 | 0.1 | 0% | 0 | 992 |
| Jun | 104 | 79 | 0.0 | 0% | 0 | 1242 |
| Jul | 107 | 85 | 0.9 | 0% | 0 | 1411 |
| Aug | 105 | 84 | 0.9 | 0% | 0 | 1375 |
| Sep | 100 | 78 | 0.6 | 0% | 0 | 1177 |
| Oct | 89 | 66 | 0.6 | 0% | 0 | 849 |
| Nov | 77 | 54 | 0.6 | 0% | 0 | 454 |
| Dec | 66 | 45 | 0.7 | 6% | <1 | 190 |
Monthly normals 1991–2020 at Phoenix Sky Harbor International Airport, AZ (1,107 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, 9 miles south of Phoenix, has a 32°F night in 94% of winters against 18% here, and a coolest-month low 4°F colder (41°F).
When it snows in Phoenix, Arizona
Measurable snow is rare here: only 0 of 17 winters from 1991 to 2020 recorded 0.1 inch or more at South Phoenix, AZ, 8.9 miles away, so there is no typical first-snow date to plan around.
Where these figures come from
ZIP 85015 is 8 miles from Phoenix Sky Harbor International Airport, AZ, which stands at 1,107 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 12 other ZIP codes share the station; its figures are presented in full for 85008 (Phoenix). The 2023 USDA Plant Hardiness Zone Map lists ZIP 85015 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.