Fall in zone 9aPhoto: George Chernilevsky, Public domain, via Wikimedia Commons
Frost dates for ZIP 85623 (Mammoth, AZ)
Average last spring and first fall frost dates with 10%, 50% and 90% odds, from NOAA's 1991–2020 climate normals for the nearest weather station, Oracle Sp, AZ (4 miles away).
- Average last spring frostMar 2950% chance of a 32°F freeze after this date
- Average first fall frostNov 1350% chance of a 32°F freeze by this date
- Growing season (frost-free)225 daysmedian, 32°F threshold
- USDA hardiness zone9a20 to 25°F avg. coldest night
Get The Dial for 85623 (Mammoth)
Frost and freeze alerts from the NWS forecast for 85623, the spring soil-temperature heads-up for pre-emergent, and a short weekly yard-timing email.
- Freeze alerts
- Soil-temp heads-up
- Weekly yard to-dos
Free. One weekly email plus alerts when your ZIP has a frost or a soil-temperature change worth acting on. After you submit, Kit (our email provider) sends a confirmation email: check your email and click the link to confirm. You aren't subscribed until you do. We collect only your email address and ZIP, sent to Kit to deliver The Dial. Unsubscribe anytime.
This week in your yard
As of Oct 18, 2026, from your frost dates, zone and soil temperature. Lawn timing · Vegetables · Pruning · Plants
Soil temperature now
2-inch depth
76°F 55°F or warmer
24-hour average · latest 73°F, as of Oct 18, 1:00 AM CDT
Estimate Not a measurement at this ZIP: distance-weighted average of Tucson 11 W (36 mi).
4-inch depth
76°F 55°F or warmer
24-hour average · latest 75°F, as of Oct 18, 1:00 AM CDT
Estimate Not a measurement at this ZIP: distance-weighted average of Tucson 11 W (36 mi).
Fall: Texas A&M AgriLife times fall pre-emergent (for winter weeds such as annual bluegrass) to soil cooling to about 70°F for several days. The 50–55°F band is the spring trigger. Always read and follow the product label.
7-day forecast and frost risk
The latest National Weather Service 7-day forecast and any Frost Advisory or Freeze Warning for 85623 load here. You can also open the NWS forecast for this ZIP.
Pre-emergent
Soil is 76°F at 4 inches (estimated soil temperature, not a station reading). Fall pre-emergent (annual bluegrass, winter weeds): not yet. Apply as soil cools toward 70°F (typically September to October).
Fertilizer window
Lawn region: Arid Southwest (low desert). Timing only; always follow the product label.
- Bermudagrass (warm-season): Spring: Several weeks after the lawn is fully green (April–May) (about May 14 here, using green-up about 3–4 weeks after your average last frost); Summer: Every 4–6 weeks through mid-August (heaviest feeder of the group); Late: Light, low-nitrogen/high-potassium feeding about 4 weeks before first frost, or skip. Avoid: Heavy late-fall nitrogen (linked to spring dead spot).
- Perennial ryegrass (cool-season): Early fall: September; Late fall: October–November; Overseeded Bermuda: Light feeding once the winter rye is established, if needed. Avoid: Summer feeding.
Plant now
Prune now
No frost-timed pruning windows are open this week.
Your average first frost is Nov 13: skip heavy pruning in the 6–8 weeks before it, because new growth may not harden off in time.
Spring-flowering shrubs are pruned right after their flowers fade, not by date. See the pruning guide.
Last spring frost odds
| Chance of a 32°F freeze after this date | Date |
|---|---|
| 90% (early: most years still freeze after this) | Mar 6 |
| 50% (the "average" last frost) | Mar 29 |
| 10% (cautious: only 1 year in 10 freezes later) | Apr 29 |
Most gardeners plant frost-tender crops (tomatoes, peppers, basil) after the 50% date, and closer to the 10% date for less risk.
First fall frost odds
| Chance the first 32°F freeze has happened by this date | Date |
|---|---|
| 10% (early: 1 year in 10 freezes this soon) | Oct 26 |
| 50% (the "average" first frost) | Nov 13 |
| 90% (late: most years have frozen by now) | Nov 30 |
Light frost, freeze and hard freeze
| Threshold | Last spring (50%) | First fall (50%) |
|---|---|---|
| 36°F (light frost possible on clear, calm nights) | Apr 16 | Nov 1 |
| 32°F (freeze) | Mar 29 | Nov 13 |
| 28°F (hard freeze) | Mar 9 | Nov 24 |
n/a means NOAA did not publish a date at that threshold for this station (usually because it rarely gets that cold).
Vegetable planting calendar for 85623
Dates count from your average last spring frost (Mar 29) and first fall frost (Nov 13). Half of years have a frost after the spring date, so give tender crops (tomatoes, peppers, squash) some slack.
| Crop | Start indoors | Spring planting | Fall planting |
|---|---|---|---|
| Tomato | Feb 1–15 | Apr 5–19 (transplant) | Jul 17–Aug 14 (transplant) |
| Pepper (sweet and hot) | Jan 18–Feb 1 | Apr 12–26 (transplant) | Jul 24–Aug 14 (transplant) |
| Eggplant | Jan 18–Feb 1 | Apr 12–26 (transplant) | Jul 24–Aug 14 (transplant) |
| Tomatillo | Feb 1–15 | Apr 5–19 (transplant) | – |
| Lettuce | Feb 1–15 | Mar 8–29 (transplant) Mar 1–Apr 12 (sow outdoors) | Sep 18–Oct 9 (transplant) Sep 4–Oct 2 (sowing) |
| Spinach | – | Feb 15–Mar 8 (sow outdoors) | Sep 18–Oct 9 (sowing) |
| Kale | Feb 1–15 | Mar 1–15 (transplant) Mar 1–15 (sow outdoors) | Aug 21–Sep 18 (transplant) Aug 7–Sep 4 (sowing) |
| Collards | Feb 1–15 | Mar 1–29 (transplant) Mar 1–29 (sow outdoors) | Aug 21–Sep 18 (transplant) Aug 7–Sep 4 (sowing) |
| Broccoli | Jan 18–Feb 1 | Mar 1–15 (transplant) | Aug 7–Sep 4 (transplant) |
| Cabbage | Jan 18–Feb 1 | Mar 1–15 (transplant) | Aug 7–Sep 4 (transplant) |
| Cauliflower | Jan 18–Feb 1 | Mar 15–29 (transplant) | Aug 7–Sep 4 (transplant) |
| Brussels sprouts | Jan 4–18 | Mar 1–15 (transplant) | Jul 24–Aug 14 (transplant) |
| Kohlrabi | Feb 1–15 | Mar 1–15 (transplant) Mar 1–15 (sow outdoors) | Sep 4–18 (sowing) |
| Bok choy / Asian greens | – | Mar 1–15 (sow outdoors) | Sep 18–Oct 2 (sowing) |
| Arugula | – | Mar 1–29 (sow outdoors) | Sep 18–Oct 16 (sowing) |
| Mustard greens | – | Mar 1–22 (sow outdoors) | Sep 18–Oct 2 (sowing) |
| Swiss chard | Feb 15–Mar 1 | Mar 15–Apr 5 (transplant) Mar 15–Apr 12 (sow outdoors) | Sep 4–18 (sowing) |
| Beet | – | Mar 1–29 (sow outdoors) | Sep 4–18 (sowing) |
| Carrot | – | Mar 8–Apr 5 (sow outdoors) | Aug 21–Sep 4 (sowing) |
| Radish | – | Feb 22–Apr 5 (sow outdoors) | Oct 2–16 (sowing) |
| Turnip | – | Mar 1–22 (sow outdoors) | Sep 4–18 (sowing) |
| Parsnip | – | Mar 8–29 (sow outdoors) | – |
| Pea (garden, snap, snow) | – | Feb 1–Mar 1 (sow outdoors) | Aug 21–Sep 4 (sowing) |
| Onion (bulbing) | Jan 4–18 | Feb 15–Mar 1 (transplant) | – |
| Green onion / scallion | – | Feb 15–Mar 15 (sow outdoors) | Sep 4–18 (sowing) |
| Leek | Jan 4–18 | Mar 1–15 (transplant) | – |
| Garlic | – | – | Oct 2–30 (sowing) |
| Shallot | – | Feb 15–Mar 1 (transplant) | Oct 2–30 (sowing) |
| Potato | – | Mar 1–15 (transplant) | Jul 24–Aug 7 (transplant) |
| Sweet potato | – | Apr 19–May 3 (transplant) | – |
| Sweet corn | – | Apr 5–19 (sow outdoors) | – |
| Bean, bush (snap) | – | Apr 5–19 (sow outdoors) | Aug 21–Sep 4 (sowing) |
| Bean, pole | – | Apr 5–19 (sow outdoors) | – |
| Lima bean | – | Apr 12–26 (sow outdoors) | – |
| Southern pea (cowpea, black-eyed pea) | – | Apr 19–May 10 (sow outdoors) | – |
| Cucumber | Mar 1–8 | Apr 5–19 (transplant) Apr 5–19 (sow outdoors) | Aug 21–Sep 4 (sowing) |
| Summer squash / zucchini | Mar 1–8 | Apr 5–19 (transplant) Apr 5–19 (sow outdoors) | Aug 21–Sep 4 (sowing) |
| Winter squash | Mar 1–8 | Apr 5–19 (transplant) Apr 5–19 (sow outdoors) | – |
| Pumpkin | – | Apr 5–19 (sow outdoors) | – |
| Watermelon | Mar 1–8 | Apr 12–26 (transplant) Apr 12–26 (sow outdoors) | – |
| Cantaloupe / muskmelon | Mar 1–8 | Apr 12–26 (transplant) Apr 12–26 (sow outdoors) | – |
| Okra | Feb 15–Mar 1 | Apr 12–26 (transplant) Apr 12–26 (sow outdoors) | – |
| Celery | Jan 4–18 | Apr 5–12 (transplant) | – |
| Basil | Feb 15–Mar 1 | Apr 5–19 (transplant) Apr 5–19 (sow outdoors) | – |
| Cilantro | – | Mar 15–Apr 12 (sow outdoors) | Sep 18–Oct 2 (sowing) |
| Parsley | Jan 18–Feb 1 | Mar 15–29 (transplant) Mar 8–29 (sow outdoors) | – |
| Dill | – | Mar 29–Apr 12 (sow outdoors) | Sep 18–Oct 2 (sowing) |
| Sunflower | – | Mar 29–Apr 12 (sow outdoors) | – |
| Asparagus (crowns) | – | Mar 1–15 (transplant) | – |
| Rhubarb (crowns) | – | Mar 1–15 (transplant) | – |
| Strawberry (plants) | – | Mar 1–15 (transplant) | Sep 4–Oct 2 (transplant) |
Typical ranges from university extension planting calendars, adjusted to your frost dates. Probabilities, not guarantees. Fall windows that would overlap spring planting are left out, as are fall crops of frost-tender plants where the frost-free season is under 210 days.
Where these numbers come from
Station: Oracle Sp, AZ (NOAA GHCN-Daily ID USC00026117), elevation 4,595 ft, 4.3 miles from the ZIP's center point. NOAA completeness flag: R (representative, 10+ years).
Nearby stations
| Station | Distance | Last frost (50%) | First frost (50%) |
|---|---|---|---|
| Oracle 2 SE, AZ | 5 mi | Mar 23 | Nov 22 |
| San Manuel, AZ | 10 mi | Feb 4 | Dec 8 |
| Catalina Sp, AZ | 18 mi | Apr 2 | Nov 11 |
The average last-frost dates of these stations span 60 days, a rough guide to local variation. See data sources & methods.
Frost questions for 85623
When is the last frost in 85623?
The average (50% chance) last spring freeze of 32°F for ZIP 85623 is March 29. For a more cautious planting date, use April 29, when only 1 year in 10 still sees a later freeze.
When is the first frost in 85623?
The average first fall freeze is November 13. In 1 year in 10 it comes by October 26.
What hardiness zone is 85623?
ZIP 85623 is in USDA zone 9a (20 to 25°F average coldest winter night), per the 2023 USDA Plant Hardiness Zone Map ZIP listing.
What is the soil temperature in 85623 right now?
This page shows the latest 2-inch and 4-inch soil temperature from the nearest public soil station (USDA SCAN, NOAA USCRN or TexMesonet), or a labeled estimate when no station is close, against the 50–55°F spring pre-emergent band.
Nearby ZIP codes
85618 85739 Saddlebrooke 85631 San Manuel 85755 Oro Valley 85619 Summerhaven 85737 Oro Valley 85192 Dudleyville 85658 Marana
Other ZIP codes in Pinal County
85118 85119 85120 85121 85122 85123 85128 85131 85132 85137 85138 85139 85140 85141 85142 85143 85145 85147 85172 85173 85191 85192 85193 85194 All Pinal County frost dates · Arizona frost dates
Never miss a frost: get The Dial
Weekly yard timing, plus frost and soil-temperature alerts for your ZIP code.
- Freeze alerts
- Soil-temp heads-up
- Weekly yard to-dos
Free. One weekly email plus alerts when your ZIP has a frost or a soil-temperature change worth acting on. After you submit, Kit (our email provider) sends a confirmation email: check your email and click the link to confirm. You aren't subscribed until you do. We collect only your email address and ZIP, sent to Kit to deliver The Dial. Unsubscribe anytime.