USDA Hardiness Zone 8b
Frost Dates for 85540 — Morenci, Arizona
NOAA 1991–2020 normals from Clifton, AZ (3,520 ft), 2 miles northeast.
Updated
In Morenci, the last spring frost (32°F) is around February 26 in half of years and has passed by March 15 in nine years out of ten. The first fall frost comes around November 23, as early as November 10 one year in ten, leaving a typical freeze-free season of 268 days (NOAA, Clifton, AZ).
- Last spring frost
- February 26
- First fall frost
- November 23
- Growing season
- 268 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
- 6%
- Snow per year
- 0"
median, 1991–2020
median, 1991–2020
1 of 17 observed
NOAA normal
Frost risk by date in Morenci
Half of springs at Clifton, AZ see their last 32°F night by February 26; only one in ten is past it by February 6, and one in ten still has one after March 15. Planting tender crops after March 6 leaves a 30% risk of a frost on them, after March 10 20%, and after March 15 10%. The 17 days between the even-odds date and the one-in-ten date is narrower than at 80% of the 98 Arizona stations behind this site's ZIP pages.
In fall the first 32°F night comes by November 23 in half of years, as early as November 10 one year in ten, and holds off past December 6 one year in ten. A hard freeze of 28°F follows 12 days later, around December 5; in spring the one-in-ten date for 28°F is March 3, 12 days before the 32°F one. The freeze-free season lasts 268 days in a typical year, longer than at 60% of the 98 Arizona stations; it reaches 296 days one year in ten and falls short of 244 one year in ten. On average 30 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 16 days longer, to about March 14, and return around November 14. Nights of 24°F, cold enough to damage hardier plants, come in 86% of winters and 16°F in 6%.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Feb 24 | Mar 2 | Mar 6 | Mar 10 | Mar 14 | Mar 18 | Mar 24 | Mar 31 | Apr 7 |
| 32°F | Feb 6 | Feb 12 | Feb 17 | Feb 22 | Feb 26 | Mar 2 | Mar 6 | Mar 10 | Mar 15 |
| 28°F | Jan 9 | Jan 21 | Jan 29 | Feb 1 | Feb 5 | Feb 9 | Feb 15 | Feb 22 | Mar 3 |
| 24°F86% of yrs | Dec 17 | Dec 28 | Jan 4 | Jan 9 | Jan 15 | Jan 23 | Jan 30 | Feb 2 | Feb 9 |
| 20°F35% of yrs | too rare for a date | ||||||||
| 16°F6% of yrs | too rare for a date | ||||||||
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 30 | Nov 4 | Nov 8 | Nov 11 | Nov 14 | Nov 16 | Nov 19 | Nov 21 | Nov 25 |
| 32°F | Nov 10 | Nov 15 | Nov 18 | Nov 21 | Nov 23 | Nov 26 | Nov 28 | Dec 1 | Dec 6 |
| 28°F | Nov 20 | Nov 24 | Nov 28 | Dec 1 | Dec 5 | Dec 9 | Dec 13 | Dec 18 | Dec 24 |
| 24°F86% of yrs | Nov 28 | Dec 6 | Dec 12 | Dec 16 | Dec 20 | Dec 25 | Dec 29 | Jan 5 | Jan 16 |
| 20°F35% of yrs | too rare for a date | ||||||||
| 16°F6% of yrs | too rare for a date | ||||||||
Freeze probabilities 1991–2020 at Clifton, 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 85540 →Compare Morenci with another place →
Weather by month in Morenci
July is the warmest month at Clifton, AZ, averaging 100°F by day and 74°F at night; December is the coldest at 60°F and 35°F. A freezing night is all but certain in every month from December to February (a 90% chance or more). From April to October the chance of a 32°F night stays under 10% each month. In spring, March still brings one in 43% of years.
Warmth for growing adds up to 6,621 growing degree days a year (base 50°F), more than at 58% of the 102 Arizona stations. 41% of them (2,707) have built up by the end of June, and July adds the most, 1,159. Precipitation totals 17.1 inches a year, most in August (3.3") and least in June (0.4"); May to September bring 53% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 61 | 35 | 1.3 | 99% | 12 | 38 |
| Feb | 66 | 39 | 1.5 | 91% | 3 | 103 |
| Mar | 73 | 45 | 0.9 | 43% | 1 | 295 |
| Apr | 81 | 51 | 0.5 | 1% | 0 | 483 |
| May | 90 | 59 | 0.5 | 0% | 0 | 755 |
| Jun | 100 | 69 | 0.4 | 0% | 0 | 1033 |
| Jul | 100 | 74 | 3.1 | 0% | 0 | 1159 |
| Aug | 98 | 72 | 3.3 | 0% | 0 | 1071 |
| Sep | 93 | 66 | 1.7 | 0% | 0 | 876 |
| Oct | 83 | 55 | 1.5 | 2% | <1 | 582 |
| Nov | 70 | 42 | 1.3 | 75% | 2 | 197 |
| Dec | 60 | 35 | 1.1 | 100% | 12 | 29 |
Monthly normals 1991–2020 at Clifton, AZ (3,520 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, Duncan, AZ, 24 miles southeast of Morenci, has a last frost 57 days later (April 24), a first frost 29 days earlier (October 25), a season 85 days shorter.
When it snows in Morenci, Arizona
Measurable snow is rare here: only 1 of 17 winters from 1991 to 2020 recorded 0.1 inch or more at Clifton, AZ, 1.5 miles away, so there is no typical first-snow date to plan around.
Planting calendar for 85540
| When | What to do |
|---|---|
| December 18 – January 1 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| January 1 – January 15 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| January 29 – February 12 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| February 26 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by August 31 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by November 9 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| November 23 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 85540 is 2 miles from Clifton, AZ, which stands at 3,520 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 1 other ZIP code shares the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 85540 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.