USDA Hardiness Zone 9a
Frost Dates for 85749 — Tucson, Arizona
NOAA 1991–2020 normals from Mt Lemmon Willow Canyon, AZ (7,027 ft), 7 miles northeast.
Updated
In Tucson, the last spring frost (32°F) is around April 1 in half of years and has passed by April 21 in nine years out of ten. The first fall frost comes around November 19, as early as October 30 one year in ten, leaving a typical freeze-free season of 229 days (NOAA, Mt Lemmon Willow Canyon, AZ).
- Last spring frost
- April 1
- First fall frost
- November 19
- Growing season
- 229 days
- Hardiness zone
- 9a
50% probability
50% probability
freeze-free, 50%
20 to 25°F (-6.7 to -3.9°C) coldest night
- First snow
- Rare
- Last snow
- Rare
- Winters with snow
- 0%
- Snow per year
- 0"
median, 1991–2020
median, 1991–2020
0 of 20 observed
NOAA normal
Frost risk by date in Tucson
Half of springs at Mt Lemmon Willow Canyon, 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 21. Planting tender crops after April 8 leaves a 30% risk of a frost on them, after April 13 20%, and after April 21 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 19 in half of years, as early as October 30 one year in ten, and holds off past December 4 one year in ten. A hard freeze of 28°F follows 11 days later, around November 30; in spring the one-in-ten date for 28°F is April 6, 15 days before the 32°F one. The freeze-free season lasts 229 days in a typical year, longer than at 50% of the 98 Arizona stations; it reaches 254 days one year in ten and falls short of 203 one year in ten. On average 53 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 April 17, and return around November 5. Nights of 24°F, cold enough to damage hardier plants, come in 98% of winters and 16°F in 26%.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 3 | Apr 8 | Apr 11 | Apr 13 | Apr 17 | Apr 21 | Apr 25 | Apr 29 | May 4 |
| 32°F | Mar 13 | Mar 19 | Mar 24 | Mar 28 | Apr 1 | Apr 5 | Apr 8 | Apr 13 | Apr 21 |
| 28°F | Feb 19 | Feb 28 | Mar 4 | Mar 7 | Mar 12 | Mar 16 | Mar 22 | Mar 29 | Apr 6 |
| 24°F98% of yrs | Jan 3 | Jan 30 | Feb 9 | Feb 16 | Feb 20 | Feb 26 | Mar 2 | Mar 7 | Mar 11 |
| 20°F68% of yrs | Dec 14 | Dec 25 | Jan 4 | Jan 25 | Feb 5 | Feb 11 | Feb 18 | Feb 24 | Mar 2 |
| 16°F26% of yrs | too rare for a date | ||||||||
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 19 | Oct 24 | Oct 29 | Nov 1 | Nov 5 | Nov 10 | Nov 14 | Nov 18 | Nov 24 |
| 32°F | Oct 30 | Nov 5 | Nov 11 | Nov 15 | Nov 19 | Nov 22 | Nov 25 | Nov 30 | Dec 4 |
| 28°F | Nov 11 | Nov 18 | Nov 23 | Nov 27 | Nov 30 | Dec 4 | Dec 6 | Dec 10 | Dec 17 |
| 24°F98% of yrs | Nov 24 | Dec 1 | Dec 6 | Dec 10 | Dec 14 | Dec 19 | Dec 24 | Jan 2 | Jan 26 |
| 20°F68% of yrs | Dec 5 | Dec 12 | Dec 17 | Dec 23 | Dec 30 | Jan 11 | Feb 1 | Feb 9 | Feb 18 |
| 16°F26% of yrs | too rare for a date | ||||||||
Freeze probabilities 1991–2020 at Mt Lemmon Willow Canyon, 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 85749 →Compare Tucson with another place →
Compared with the next station
The nearest other station, Saguaro Np, AZ, 8 miles south of Tucson and 3,947 feet lower, has a last frost 65 days earlier (January 26), a first frost 27 days later (December 16), a season 97 days longer.
When it snows in Tucson, Arizona
Measurable snow is rare here: only 0 of 20 winters from 1991 to 2020 recorded 0.1 inch or more at Tucson Camp Ave Exp, AZ, 11.7 miles away, so there is no typical first-snow date to plan around.
Planting calendar for 85749
| 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 27 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by November 5 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| November 19 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 85749 is 7 miles from Mt Lemmon Willow Canyon, AZ, which stands at 7,027 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 85749 in zone 9a, the band where the coldest night of the year averaged 20 to 25°F (-6.7 to -3.9°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.