USDA Hardiness Zone 8b
Frost Dates for 85615 — Hereford, Arizona
NOAA 1991–2020 normals from Coronado Nmem, AZ (5,242 ft), 6 miles south.
Updated
In Hereford, the last spring frost (32°F) is around April 7 in half of years and has passed by April 27 in nine years out of ten. The first fall frost comes around November 9, as early as October 25 one year in ten, leaving a typical freeze-free season of 213 days (NOAA, Coronado Nmem, AZ).
- Last spring frost
- April 7
- First fall frost
- November 9
- Growing season
- 213 days
- Hardiness zone
- 8b
50% probability
50% probability
freeze-free, 50%
15 to 20°F (-9.4 to -6.7°C) coldest night
- First snow
- Rare
- Last snow
- Rare
- Winters with snow
- 40%
- Snow per year
- 0.7"
median, 1991–2020
median, 1991–2020
8 of 20 observed
NOAA normal
Frost risk by date in Hereford
Half of springs at Coronado Nmem, AZ see their last 32°F night by April 7; only one in ten is past it by March 19, and one in ten still has one after April 27. Planting tender crops after April 15 leaves a 30% risk of a frost on them, after April 20 20%, and after April 27 10%. The 20 days between the even-odds date and the one-in-ten date is narrower than at 52% of the 98 Arizona stations behind this site's ZIP pages.
In fall the first 32°F night comes by November 9 in half of years, as early as October 25 one year in ten, and holds off past November 27 one year in ten. A hard freeze of 28°F follows 11 days later, around November 20; in spring the one-in-ten date for 28°F is April 12, 15 days before the 32°F one. The freeze-free season lasts 213 days in a typical year, shorter than at 63% of the 98 Arizona stations; it reaches 238 days one year in ten and falls short of 189 one year in ten. On average 54 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 17 days longer, to about April 24, and return around October 31. Nights of 24°F, cold enough to damage hardier plants, come in 100% of winters and 16°F in 45%.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 5 | Apr 12 | Apr 16 | Apr 21 | Apr 24 | Apr 28 | May 1 | May 5 | May 12 |
| 32°F | Mar 19 | Mar 27 | Mar 31 | Apr 4 | Apr 7 | Apr 11 | Apr 15 | Apr 20 | Apr 27 |
| 28°F | Feb 22 | Mar 1 | Mar 7 | Mar 13 | Mar 19 | Mar 24 | Mar 30 | Apr 4 | Apr 12 |
| 24°F | Jan 23 | Feb 3 | Feb 10 | Feb 16 | Feb 22 | Feb 28 | Mar 6 | Mar 12 | Mar 25 |
| 20°F90% of yrs | Dec 26 | Jan 4 | Jan 13 | Jan 23 | Jan 31 | Feb 5 | Feb 11 | Feb 17 | Feb 26 |
| 16°F45% of yrs | too rare for a date | ||||||||
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 16 | Oct 21 | Oct 25 | Oct 28 | Oct 31 | Nov 2 | Nov 5 | Nov 9 | Nov 14 |
| 32°F | Oct 25 | Oct 30 | Nov 2 | Nov 5 | Nov 9 | Nov 12 | Nov 16 | Nov 20 | Nov 27 |
| 28°F | Nov 1 | Nov 8 | Nov 12 | Nov 16 | Nov 20 | Nov 24 | Nov 28 | Dec 3 | Dec 7 |
| 24°F | Nov 13 | Nov 20 | Nov 26 | Nov 30 | Dec 4 | Dec 7 | Dec 13 | Dec 19 | Dec 26 |
| 20°F90% of yrs | Nov 28 | Dec 7 | Dec 13 | Dec 19 | Dec 23 | Dec 28 | Jan 3 | Jan 13 | Jan 28 |
| 16°F45% of yrs | too rare for a date | ||||||||
Freeze probabilities 1991–2020 at Coronado Nmem, 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 85615 →Compare Hereford with another place →
Weather by month in Hereford
June is the warmest month at Coronado Nmem, AZ, averaging 92°F by day and 60°F at night; January is the coldest at 59°F and 33°F. A freezing night is all but certain in every month from November to March (a 90% chance or more). From May to September the chance of a 32°F night stays under 10% each month. In spring, April still brings one in 68% of years.
Warmth for growing adds up to 4,648 growing degree days a year (base 50°F), fewer than at 66% of the 102 Arizona stations. 40% of them (1,866) have built up by the end of June, and July adds the most, 801. Precipitation totals 20.9 inches a year, most in August (4.8") and least in May (0.2"); May to September bring 60% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 59 | 33 | 1.6 | 100% | 15 | 28 |
| Feb | 62 | 35 | 1.5 | 100% | 10 | 55 |
| Mar | 68 | 39 | 1.0 | 97% | 6 | 160 |
| Apr | 75 | 45 | 0.3 | 68% | 3 | 310 |
| May | 83 | 52 | 0.2 | 7% | <1 | 535 |
| Jun | 92 | 60 | 0.9 | 0% | 0 | 778 |
| Jul | 89 | 63 | 4.6 | 0% | 0 | 801 |
| Aug | 87 | 62 | 4.8 | 0% | 0 | 746 |
| Sep | 84 | 58 | 2.1 | 0% | 0 | 633 |
| Oct | 77 | 50 | 1.2 | 25% | 1 | 417 |
| Nov | 67 | 40 | 0.8 | 92% | 5 | 154 |
| Dec | 58 | 34 | 1.9 | 100% | 15 | 32 |
Monthly normals 1991–2020 at Coronado Nmem, AZ (5,242 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, Sierra Vista, AZ, 8 miles north of Hereford and 636 feet lower, has a last frost 2 days earlier (April 5), the same first-frost date, a season 3 days longer.
When it snows in Hereford, Arizona
Measurable snow is rare here: only 8 of 20 winters from 1991 to 2020 recorded 0.1 inch or more at Y Lightning Rch, AZ, 1.6 miles away, so there is no typical first-snow date to plan around.
Planting calendar for 85615
| When | What to do |
|---|---|
| January 27 – February 10 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| February 10 – February 24 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| March 10 – March 24 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| April 7 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by August 17 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by October 26 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| November 9 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 85615 is 6 miles from Coronado Nmem, AZ, which stands at 5,242 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 85615 in zone 8b, the band where the coldest night of the year averaged 15 to 20°F (-9.4 to -6.7°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.