Mount Lemmon, AZ frost dates
Last spring frostApr 1median date
First fall frostNov 19median date
Growing season232 daysfrost-free
Hardiness zone8bZone 8b
How Mount Lemmon compares
- In 8 years out of 10, the last spring frost in Mount Lemmon falls between March 13 and April 21, a 39-day window. The first fall frost falls between October 30 and December 4.
- The median last frost is 15 days earlier than the Arizona median of Apr 16.
- Its 232-day growing season is longer than 76% of the 193 Arizona places with a regular frost season (state median 197 days).
- The last frost is 16 days later than the zone 8b median of Mar 16. Hardiness zones measure winter cold, not season length, so use these dates rather than a zone 8b chart.
- The weather station records an average of 53 nights a year at or below 32°F.
- Nearby Tucson, AZ, 24 km away, gets only light, occasional frost, a reminder of how much elevation and distance from the coast matter.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | March 13 |
| 50% (median) | April 1 |
| 10% (safe for tender plants) | April 21 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | October 30 |
| 50% (median) | November 19 |
| 90% (late) | December 4 |
Frost here means 32°F (0°C). A median date means half of years have their last frost earlier and half later.
Planting calendar for Mount Lemmon, AZ
Mount Lemmon, AZ frost dates — last frost Apr 1, first frost Nov 19, zone 8b. whenisthelastfrost.com
Crop
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Start indoors: Jan 7 to Jan 21Transplant outside: Mar 4 to Mar 18
Start indoors: Jan 21 to Feb 4Transplant outside: Apr 15 to Apr 29
Start indoors: Jan 21 to Feb 4Transplant outside: Apr 15 to Apr 29
Start indoors: Feb 4 to Feb 18Transplant outside: Apr 8 to Apr 22
Start indoors: Feb 4 to Feb 18Transplant outside: Mar 11 to Mar 25Sow outdoors: Mar 4 to Apr 8Plant for fall: Sep 24 to Oct 22
Start indoors: Feb 4 to Feb 18Transplant outside: Mar 4 to Mar 18Sow outdoors: Mar 4 to Mar 18Plant for fall: Sep 10 to Oct 1
Start indoors: Feb 4 to Feb 18Transplant outside: Mar 18 to Apr 1Plant for fall: Aug 13 to Sep 3
Start indoors: Feb 4 to Feb 18Transplant outside: Mar 11 to Mar 25Plant for fall: Aug 13 to Sep 3
Start indoors: Feb 4 to Feb 18Transplant outside: Mar 18 to Apr 1Plant for fall: Aug 13 to Sep 3
Start indoors: Feb 18 to Mar 4Transplant outside: Apr 22 to May 6Sow outdoors: Apr 22 to May 6
Start indoors: Feb 18 to Mar 4Transplant outside: Apr 8 to Apr 22
Sow outdoors: Feb 18 to Mar 11Plant for fall: Aug 27 to Sep 17
Sow outdoors: Feb 18 to Mar 11Plant for fall: Sep 24 to Oct 15
Sow outdoors: Feb 25 to Apr 8Plant for fall: Oct 8 to Oct 29
Start indoors: Mar 4 to Mar 11Transplant outside: Apr 15 to Apr 22Sow outdoors: Apr 8 to Apr 22Plant for fall: Sep 3 to Sep 17
Start indoors: Mar 4 to Mar 11Sow outdoors: Apr 8 to Apr 22Plant for fall: Sep 10 to Sep 24
Start indoors: Mar 4 to Mar 11Sow outdoors: Apr 8 to Apr 22
Start indoors: Mar 4 to Mar 11Transplant outside: Apr 15 to Apr 29
Sow outdoors: Mar 11 to Apr 8Plant for fall: Aug 27 to Sep 10
Sow outdoors: Mar 11 to Apr 8Plant for fall: Sep 10 to Sep 24
Sow outdoors: Mar 11 to Apr 1
Sow outdoors: Mar 18 to Apr 15Plant for fall: Sep 10 to Sep 24
Sow outdoors: Mar 18 to Apr 8Plant for fall: Sep 24 to Oct 15
Sow outdoors: Apr 8 to Apr 29Plant for fall: Sep 3 to Sep 17
Sow outdoors: Apr 8 to Apr 22
Transplant outside: Apr 15 to May 6
Plant for fall: Nov 5 to Dec 10
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Mount Lemmon, AZ
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Jan 7 – Jan 21 | Mar 4 – Mar 18 | — | — |
| Peppers | Jan 21 – Feb 4 | Apr 15 – Apr 29 | — | — |
| Eggplant | Jan 21 – Feb 4 | Apr 15 – Apr 29 | — | — |
| Tomatoes | Feb 4 – Feb 18 | Apr 8 – Apr 22 | — | — |
| Lettuce | Feb 4 – Feb 18 | Mar 11 – Mar 25 | Mar 4 – Apr 8 | Sep 24 – Oct 22 |
| Kale | Feb 4 – Feb 18 | Mar 4 – Mar 18 | Mar 4 – Mar 18 | Sep 10 – Oct 1 |
| Broccoli | Feb 4 – Feb 18 | Mar 18 – Apr 1 | — | Aug 13 – Sep 3 |
| Cabbage | Feb 4 – Feb 18 | Mar 11 – Mar 25 | — | Aug 13 – Sep 3 |
| Cauliflower | Feb 4 – Feb 18 | Mar 18 – Apr 1 | — | Aug 13 – Sep 3 |
| Okra | Feb 18 – Mar 4 | Apr 22 – May 6 | Apr 22 – May 6 | — |
| Basil | Feb 18 – Mar 4 | Apr 8 – Apr 22 | — | — |
| Peas | — | — | Feb 18 – Mar 11 | Aug 27 – Sep 17 |
| Spinach | — | — | Feb 18 – Mar 11 | Sep 24 – Oct 15 |
| Radishes | — | — | Feb 25 – Apr 8 | Oct 8 – Oct 29 |
| Cucumbers | Mar 4 – Mar 11 | Apr 15 – Apr 22 | Apr 8 – Apr 22 | Sep 3 – Sep 17 |
| Zucchini & Summer Squash | Mar 4 – Mar 11 | — | Apr 8 – Apr 22 | Sep 10 – Sep 24 |
| Winter Squash & Pumpkins | Mar 4 – Mar 11 | — | Apr 8 – Apr 22 | — |
| Melons & Watermelon | Mar 4 – Mar 11 | Apr 15 – Apr 29 | — | — |
| Carrots | — | — | Mar 11 – Apr 8 | Aug 27 – Sep 10 |
| Beets | — | — | Mar 11 – Apr 8 | Sep 10 – Sep 24 |
| Potatoes | — | — | Mar 11 – Apr 1 | — |
| Swiss Chard | — | — | Mar 18 – Apr 15 | Sep 10 – Sep 24 |
| Cilantro | — | — | Mar 18 – Apr 8 | Sep 24 – Oct 15 |
| Green Beans | — | — | Apr 8 – Apr 29 | Sep 3 – Sep 17 |
| Sweet Corn | — | — | Apr 8 – Apr 22 | — |
| Sweet Potatoes | — | Apr 15 – May 6 | — | — |
| Garlic | — | — | — | Nov 5 – Dec 10 |
Dates come from the median frost dates and common extension-service timing. Adjust for your soil temperature, microclimate and the varieties you grow.
About these dates
Based on 1991–2020 NOAA climate normals for the Mt Lemmon Willow Canyon, AZ weather station, 6 km away (elevation 7,028 ft (2,142 m)).
Frost dates near Mount Lemmon
- Catalina Apr 2 · Nov 11
- Tucson Jan 20 · Dec 17
- Oracle Mar 23 · Nov 22
- San Manuel Feb 4 · Dec 8
- Cortaro Feb 26 · Dec 4
- Rillito Feb 23 · Dec 6
- Mammoth Feb 4 · Dec 8
- Vail Jan 26 · Dec 16
- Marana Feb 23 · Dec 6
- Sahuarita Feb 25 · Nov 27
Frequently asked questions
When is the last frost in Mount Lemmon, AZ?
The median last spring frost in Mount Lemmon, AZ is April 1. There is still about a 10% chance of frost after April 21, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Mount Lemmon, AZ?
The median first fall frost is November 19, with about a 10% chance of frost before October 30.
How long is the growing season in Mount Lemmon, AZ?
About 232 days between the median last spring frost and first fall frost.
What planting zone is Mount Lemmon, AZ?
Mount Lemmon, AZ is in USDA hardiness zone 8b.