USDA Hardiness Zone 8b
Frost Dates for 86326 — Cottonwood, Arizona
NOAA 1991–2020 normals from Tuzigoot, AZ (3,470 ft), 3 miles north.
Updated
In Cottonwood, the last spring frost (32°F) is around March 30 in half of years and has passed by April 21 in nine years out of ten. The first fall frost comes around November 10, as early as October 25 one year in ten, leaving a typical freeze-free season of 223 days (NOAA, Tuzigoot, AZ).
- Last spring frost
- March 30
- First fall frost
- November 10
- Growing season
- 223 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
- 45%
- Snow per year
- 1"
median, 1991–2020
median, 1991–2020
13 of 29 observed
NOAA normal
Frost risk by date in Cottonwood
Half of springs at Tuzigoot, AZ see their last 32°F night by March 30; only one in ten is past it by March 9, and one in ten still has one after April 21. Planting tender crops after April 6 leaves a 30% risk of a frost on them, after April 11 20%, and after April 21 10%. The 22 days between the even-odds date and the one-in-ten date is wider than at 54% 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 November 10 in half of years, as early as October 25 one year in ten, and holds off past November 23 one year in ten. A hard freeze of 28°F follows 10 days later, around November 20; in spring the one-in-ten date for 28°F is March 31, 21 days before the 32°F one. The freeze-free season lasts 223 days in a typical year, shorter than at 55% of the 98 Arizona stations; it reaches 248 days one year in ten and falls short of 199 one year in ten. On average 63 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 18 days longer, to about April 17, and return around October 31. Nights of 24°F, cold enough to damage hardier plants, come in 100% of winters and 16°F in 39%.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Mar 29 | Apr 4 | Apr 8 | Apr 13 | Apr 17 | Apr 22 | Apr 26 | Apr 30 | May 6 |
| 32°F | Mar 9 | Mar 15 | Mar 19 | Mar 25 | Mar 30 | Apr 2 | Apr 6 | Apr 11 | Apr 21 |
| 28°F | Feb 14 | Feb 22 | Feb 27 | Mar 2 | Mar 5 | Mar 9 | Mar 14 | Mar 18 | Mar 31 |
| 24°F | Jan 18 | Jan 29 | Feb 4 | Feb 8 | Feb 13 | Feb 18 | Feb 22 | Feb 27 | Mar 5 |
| 20°F91% of yrs | Dec 22 | Jan 1 | Jan 8 | Jan 17 | Jan 24 | Feb 1 | Feb 6 | Feb 12 | Feb 20 |
| 16°F39% of yrs | too rare for a date | ||||||||
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 17 | Oct 21 | Oct 25 | Oct 28 | Oct 31 | Nov 2 | Nov 5 | Nov 8 | Nov 12 |
| 32°F | Oct 25 | Nov 1 | Nov 4 | Nov 7 | Nov 10 | Nov 13 | Nov 15 | Nov 18 | Nov 23 |
| 28°F | Nov 5 | Nov 10 | Nov 15 | Nov 17 | Nov 20 | Nov 23 | Nov 27 | Dec 1 | Dec 5 |
| 24°F | Nov 17 | Nov 22 | Nov 26 | Nov 30 | Dec 3 | Dec 6 | Dec 10 | Dec 14 | Dec 20 |
| 20°F91% of yrs | Nov 29 | Dec 4 | Dec 8 | Dec 12 | Dec 17 | Dec 23 | Dec 29 | Jan 5 | Jan 20 |
| 16°F39% of yrs | too rare for a date | ||||||||
Freeze probabilities 1991–2020 at Tuzigoot, 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 86326 →Compare Cottonwood with another place →
Weather by month in Cottonwood
July is the warmest month at Tuzigoot, AZ, averaging 101°F by day and 67°F at night; December is the coldest at 60°F and 29°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 44% of years.
Warmth for growing adds up to 5,464 growing degree days a year (base 50°F), fewer than at 54% of the 102 Arizona stations. 37% of them (2,039) have built up by the end of June, and July adds the most, 1,052. Precipitation totals 12.0 inches a year, most in August (2.2") and least in June (0.2"); May to September bring 48% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 61 | 30 | 1.1 | 100% | 19 | 15 |
| Feb | 65 | 33 | 1.0 | 100% | 11 | 50 |
| Mar | 71 | 38 | 1.0 | 94% | 4 | 166 |
| Apr | 79 | 43 | 0.4 | 44% | 1 | 334 |
| May | 88 | 51 | 0.4 | 2% | 0 | 600 |
| Jun | 99 | 59 | 0.2 | 0% | 0 | 873 |
| Jul | 101 | 67 | 1.6 | 0% | 0 | 1052 |
| Aug | 98 | 66 | 2.2 | 0% | 0 | 990 |
| Sep | 93 | 58 | 1.3 | 0% | 0 | 772 |
| Oct | 83 | 47 | 1.0 | 20% | <1 | 456 |
| Nov | 71 | 36 | 0.7 | 98% | 8 | 141 |
| Dec | 60 | 29 | 1.1 | 100% | 20 | 13 |
Monthly normals 1991–2020 at Tuzigoot, AZ (3,470 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, Montezuma Castle Nm, AZ, 13 miles southeast of Cottonwood and 290 feet lower, has a last frost 17 days later (April 16), a first frost 11 days earlier (October 30), a season 27 days shorter.
When it snows in Cottonwood, Arizona
Measurable snow is rare here: only 13 of 29 winters from 1991 to 2020 recorded 0.1 inch or more at Tuzigoot, AZ, 3.4 miles away, so there is no typical first-snow date to plan around.
Planting calendar for 86326
| When | What to do |
|---|---|
| January 19 – February 2 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| February 2 – February 16 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| March 2 – March 16 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| March 30 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by August 18 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by October 27 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| November 10 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 86326 is 3 miles from Tuzigoot, AZ, which stands at 3,470 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 2 other ZIP codes share the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 86326 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.