USDA Hardiness Zone 8a
Frost Dates for 85608 — ZIP 85608
NOAA 1991–2020 normals from Portal 4 SW, AZ (5,390 ft), 22 miles north.
Updated
In ZIP 85608, the last spring frost (32°F) is around May 3 in half of years and has passed by May 16 in nine years out of ten. The first fall frost comes around October 25, as early as October 11 one year in ten, leaving a typical freeze-free season of 174 days (NOAA, Portal 4 SW, AZ).
- Last spring frost
- May 3
- First fall frost
- October 25
- Growing season
- 174 days
- Hardiness zone
- 8a
50% probability
50% probability
freeze-free, 50%
10 to 15°F (-12.2 to -9.4°C) coldest night
- First snow
- Rare
- Last snow
- Rare
- Winters with snow
- 25%
- Snow per year
- 0.5"
median, 1991–2020
median, 1991–2020
5 of 20 observed
NOAA normal
Frost risk by date in ZIP 85608
Half of springs at Portal 4 SW, AZ see their last 32°F night by May 3; only one in ten is past it by April 16, and one in ten still has one after May 16. Planting tender crops after May 8 leaves a 30% risk of a frost on them, after May 11 20%, and after May 16 10%. The 13 days between the even-odds date and the one-in-ten date measure how much the end of the frost season moves from year to year.
In fall the first 32°F night comes by October 25 in half of years, as early as October 11 one year in ten, and holds off past November 6 one year in ten. A hard freeze of 28°F follows 10 days later, around November 4; in spring the one-in-ten date for 28°F is May 5, 11 days before the 32°F one. The freeze-free season lasts 174 days in a typical year; it reaches 193 days one year in ten and falls short of 156 one year in ten. On average 136 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 12 days longer, to about May 15, and return around October 14. Severe cold of 16°F or below comes in 98% of winters, usually between December 13 and February 2.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 1 | May 4 | May 8 | May 12 | May 15 | May 17 | May 20 | May 24 | May 30 |
| 32°F | Apr 16 | Apr 24 | Apr 27 | Apr 30 | May 3 | May 5 | May 8 | May 11 | May 16 |
| 28°F | Mar 30 | Apr 4 | Apr 8 | Apr 12 | Apr 16 | Apr 20 | Apr 24 | Apr 29 | May 5 |
| 24°F | Mar 3 | Mar 10 | Mar 15 | Mar 20 | Mar 26 | Mar 31 | Apr 3 | Apr 8 | Apr 17 |
| 20°F | Feb 3 | Feb 11 | Feb 17 | Feb 22 | Feb 27 | Mar 3 | Mar 8 | Mar 14 | Mar 25 |
| 16°F98% of yrs | Jan 2 | Jan 12 | Jan 22 | Jan 29 | Feb 2 | Feb 6 | Feb 11 | Feb 19 | Feb 27 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 1 | Oct 5 | Oct 8 | Oct 11 | Oct 14 | Oct 17 | Oct 19 | Oct 21 | Oct 26 |
| 32°F | Oct 11 | Oct 17 | Oct 19 | Oct 22 | Oct 25 | Oct 27 | Oct 31 | Nov 2 | Nov 6 |
| 28°F | Oct 21 | Oct 26 | Oct 30 | Nov 1 | Nov 4 | Nov 6 | Nov 9 | Nov 13 | Nov 18 |
| 24°F | Nov 1 | Nov 5 | Nov 9 | Nov 12 | Nov 15 | Nov 18 | Nov 22 | Nov 26 | Nov 30 |
| 20°F | Nov 12 | Nov 18 | Nov 22 | Nov 25 | Nov 29 | Dec 1 | Dec 5 | Dec 8 | Dec 16 |
| 16°F98% of yrs | Nov 25 | Dec 1 | Dec 5 | Dec 8 | Dec 13 | Dec 19 | Dec 25 | Jan 1 | Jan 12 |
Freeze probabilities 1991–2020 at Portal 4 SW, 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 85608 →Compare ZIP 85608 with another place →
Weather by month in ZIP 85608
July is the warmest month at Portal 4 SW, AZ, averaging 88°F by day and 58°F at night; January is the coldest at 56°F and 25°F. A freezing night is all but certain in every month from November to April (a 90% chance or more). From June to September the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 59% of years.
Warmth for growing adds up to 3,390 growing degree days a year (base 50°F). 37% of them (1,238) have built up by the end of June, and July adds the most, 707. Precipitation totals 19.7 inches a year, most in August (4.4") and least in April (0.4"); May to September bring 60% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 56 | 25 | 1.4 | 100% | 27 | 3 |
| Feb | 60 | 28 | 1.1 | 100% | 22 | 15 |
| Mar | 66 | 32 | 0.9 | 100% | 21 | 56 |
| Apr | 73 | 37 | 0.4 | 99% | 12 | 172 |
| May | 81 | 43 | 0.5 | 59% | 2 | 377 |
| Jun | 89 | 52 | 0.9 | 1% | 0 | 614 |
| Jul | 88 | 58 | 3.9 | 0% | 0 | 707 |
| Aug | 85 | 57 | 4.4 | 0% | 0 | 649 |
| Sep | 81 | 51 | 2.1 | 0% | 0 | 483 |
| Oct | 75 | 41 | 1.1 | 73% | 4 | 254 |
| Nov | 64 | 32 | 1.3 | 100% | 20 | 54 |
| Dec | 55 | 26 | 1.7 | 100% | 26 | 5 |
Monthly normals 1991–2020 at Portal 4 SW, AZ (5,390 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, Douglas, AZ, 24 miles southwest of ZIP 85608 and 1,350 feet lower, has a last frost 46 days earlier (March 18), a first frost 19 days later (November 13), a season 61 days longer.
When it snows in ZIP 85608
Measurable snow is rare here: only 5 of 20 winters from 1991 to 2020 recorded 0.1 inch or more at Mc Neal, AZ, 25.7 miles away, so there is no typical first-snow date to plan around.
Planting calendar for 85608
| When | What to do |
|---|---|
| February 22 – March 8 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| March 8 – March 22 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| April 5 – April 19 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| May 3 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by August 2 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by October 11 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 25 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 85608 is 22 miles from Portal 4 SW, AZ, which stands at 5,390 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 85608 in zone 8a, the band where the coldest night of the year averaged 10 to 15°F (-12.2 to -9.4°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.