USDA Hardiness Zone 8b
Frost Dates for 85603 — Bisbee, Arizona
NOAA 1991–2020 normals from Bisbee 1WNW, AZ (5,560 ft), 4 miles northwest.
Updated
In Bisbee, the last spring frost (32°F) is around April 1 in half of years and has passed by April 20 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 222 days (NOAA, Bisbee 1WNW, AZ).
- Last spring frost
- April 1
- First fall frost
- November 10
- Growing season
- 222 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
- 25%
- Snow per year
- 0.5"
median, 1991–2020
median, 1991–2020
5 of 20 observed
NOAA normal
Frost risk by date in Bisbee
Half of springs at Bisbee 1WNW, AZ see their last 32°F night by April 1; only one in ten is past it by March 13, and one in ten still has one after April 20. Planting tender crops after April 8 leaves a 30% risk of a frost on them, after April 13 20%, and after April 20 10%. The 19 days between the even-odds date and the one-in-ten date is narrower than at 61% of the 98 Arizona stations behind this site's ZIP pages.
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 28 one year in ten. A hard freeze of 28°F follows 14 days later, around November 24; in spring the one-in-ten date for 28°F is April 4, 16 days before the 32°F one. The freeze-free season lasts 222 days in a typical year, shorter than at 56% 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 17 days longer, to about April 18, and return around October 30. Nights of 24°F, cold enough to damage hardier plants, come in 100% of winters and 16°F in 32%.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 3 | Apr 8 | Apr 12 | Apr 15 | Apr 18 | Apr 21 | Apr 25 | Apr 29 | May 4 |
| 32°F | Mar 13 | Mar 20 | Mar 25 | Mar 29 | Apr 1 | Apr 4 | Apr 8 | Apr 13 | Apr 20 |
| 28°F | Feb 16 | Feb 27 | Mar 4 | Mar 8 | Mar 13 | Mar 17 | Mar 23 | Mar 29 | Apr 4 |
| 24°F | Jan 12 | Jan 23 | Feb 1 | Feb 7 | Feb 14 | Feb 21 | Mar 1 | Mar 7 | Mar 16 |
| 20°F82% of yrs | Dec 14 | Dec 29 | Jan 5 | Jan 12 | Jan 20 | Jan 29 | Feb 3 | Feb 13 | Feb 22 |
| 16°F32% of yrs | too rare for a date | ||||||||
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 17 | Oct 21 | Oct 24 | Oct 27 | Oct 30 | Nov 1 | Nov 4 | Nov 8 | Nov 14 |
| 32°F | Oct 25 | Oct 31 | Nov 3 | Nov 6 | Nov 10 | Nov 14 | Nov 18 | Nov 23 | Nov 28 |
| 28°F | Nov 5 | Nov 11 | Nov 16 | Nov 20 | Nov 24 | Nov 28 | Dec 1 | Dec 6 | Dec 13 |
| 24°F | Nov 13 | Nov 21 | Nov 26 | Dec 2 | Dec 6 | Dec 10 | Dec 15 | Dec 21 | Jan 1 |
| 20°F82% of yrs | Nov 24 | Dec 3 | Dec 10 | Dec 19 | Dec 24 | Dec 30 | Jan 4 | Jan 13 | Jan 28 |
| 16°F32% of yrs | too rare for a date | ||||||||
Freeze probabilities 1991–2020 at Bisbee 1WNW, 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 85603 →Compare Bisbee with another place →
Weather by month in Bisbee
July is the warmest month at Bisbee 1WNW, AZ, averaging 87°F by day and 63°F at night; January is the coldest at 56°F and 32°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 52% of years.
Warmth for growing adds up to 4,228 growing degree days a year (base 50°F), fewer than at 70% of the 102 Arizona stations. 40% of them (1,681) have built up by the end of June, and July adds the most, 784. Precipitation totals 17.2 inches a year, most in August (4.3") and least in April (0.2"); May to September bring 63% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 56 | 32 | 1.3 | 100% | 18 | 12 |
| Feb | 60 | 35 | 1.1 | 100% | 12 | 36 |
| Mar | 67 | 38 | 0.9 | 97% | 7 | 126 |
| Apr | 73 | 44 | 0.2 | 52% | 2 | 268 |
| May | 81 | 51 | 0.3 | 1% | 0 | 498 |
| Jun | 89 | 60 | 0.5 | 0% | 0 | 741 |
| Jul | 87 | 63 | 3.8 | 0% | 0 | 784 |
| Aug | 85 | 61 | 4.3 | 0% | 0 | 711 |
| Sep | 82 | 57 | 2.0 | 0% | 0 | 572 |
| Oct | 75 | 48 | 1.0 | 21% | 1 | 355 |
| Nov | 64 | 39 | 0.7 | 91% | 7 | 107 |
| Dec | 56 | 33 | 1.1 | 100% | 17 | 19 |
Monthly normals 1991–2020 at Bisbee 1WNW, AZ (5,560 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, 21 miles east of Bisbee and 1,520 feet lower, has a last frost 14 days earlier (March 18), a first frost 3 days later (November 13), a season 13 days longer.
When it snows in Bisbee, Arizona
Measurable snow is rare here: only 5 of 20 winters from 1991 to 2020 recorded 0.1 inch or more at Mc Neal, AZ, 19 miles away, so there is no typical first-snow date to plan around.
Planting calendar for 85603
| When | What to do |
|---|---|
| January 21 – February 4 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| February 4 – February 18 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| March 4 – March 18 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| April 1 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 85603 is 4 miles from Bisbee 1WNW, AZ, which stands at 5,560 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 85603 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.