Frost dates for 85619Mount Lemmon, AZ
The average last spring frost in Mount Lemmon is March 23 and the average first fall frost is November 22, giving a typical growing season of about 242 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Mar 23
- Average first fall frost
- Nov 22
- Growing season
- 242 days
Safer after Apr 16 (1-in-10 risk)
Possible by Nov 2 (1-in-10 risk)
First frost typically in 26 days
Frost risk by date
NOAA reports frost dates as probabilities. The middle date is the average (a 50% chance). For spring, the 10% date is a safer planting date: frost after it happens in about 1 year in 10. Light frost (36°F) can damage tender plants; a hard freeze (28°F) kills most annuals.
| Temperature | Last spring: 90% / 50% / 10% chance | First fall: 10% / 50% / 90% chance | Growing season (50%) | Years with at least one |
|---|---|---|---|---|
| Light frost (36°F) | Mar 21 · Apr 12 · Apr 29 | Oct 23 · Nov 11 · Nov 26 | 212 days | 100% |
| Frost / freeze (32°F) | Feb 18 · Mar 23 · Apr 16 | Nov 2 · Nov 22 · Dec 7 | 242 days | 100% |
| Hard freeze (28°F) | Jan 19 · Feb 21 · Mar 30 | Nov 16 · Dec 2 · Dec 25 | 283 days | 100% |
Planting calendar for Mount Lemmon
Planting windows from the University of Maryland Extension calendar, shifted to your average frost dates. Use them as a starting point and adjust for seed packet instructions and local conditions.
| Crop | Task | Window |
|---|---|---|
| Tomatoes | Start seeds indoors | Feb 20 – Apr 28 |
| Tomatoes | Transplant outdoors | Apr 8 – Aug 2 |
| Peppers | Start seeds indoors | Feb 20 – Mar 23 |
| Peppers | Transplant outdoors | Apr 22 – May 23 |
| Eggplant | Start seeds indoors | Mar 9 – Apr 7 |
| Eggplant | Transplant outdoors | Apr 22 – May 23 |
| Cucumbers | Sow outdoors | Apr 22 – Aug 12 |
| Summer squash | Sow outdoors | Apr 8 – May 23 |
| Winter squash & pumpkins | Sow outdoors | Apr 22 – May 23 |
| Snap beans | Sow outdoors | Apr 8 – Sep 4 |
| Sweet corn | Sow outdoors | Apr 8 – Aug 2 |
| Watermelon & cantaloupe | Sow outdoors | Apr 22 – May 23 |
| Okra | Sow outdoors | Apr 15 – May 8 |
| Peas | Sow outdoors (spring) | Feb 20 – Apr 7 |
| Potatoes | Plant outdoors (spring) | Feb 20 – Apr 22 |
| Onions | Start seeds indoors (spring) | Jan 9 – Feb 5 |
| Onions | Transplant outdoors (spring) | Mar 9 – Apr 7 |
| Broccoli | Start seeds indoors (spring) | Feb 2 – Mar 8 |
| Broccoli | Transplant outdoors (spring) | Mar 9 – Apr 7 |
| Broccoli | Start seeds indoors (fall) | Jul 23 – Aug 2 |
| Broccoli | Transplant outdoors (fall) | Aug 22 – Sep 2 |
| Cabbage | Start seeds indoors (spring) | Jan 23 – Feb 20 |
| Cabbage | Transplant outdoors (spring) | Feb 20 – Mar 23 |
| Cabbage | Start seeds indoors (fall) | Jul 13 – Aug 12 |
| Cabbage | Transplant outdoors (fall) | Aug 12 – Sep 12 |
| Leaf lettuce | Sow outdoors (spring) | Feb 20 – May 8 |
| Leaf lettuce | Sow outdoors (fall) | Aug 12 – Sep 28 |
| Spinach | Sow outdoors (spring) | Feb 13 – Mar 29 |
| Spinach | Sow outdoors (fall) | Aug 29 – Oct 3 |
| Radishes | Sow outdoors (spring) | Feb 20 – Apr 12 |
| Radishes | Sow outdoors (fall) | Aug 12 – Oct 13 |
| Kale | Sow outdoors (spring) | Mar 9 – Mar 29 |
| Kale | Sow outdoors (fall) | Aug 5 – Sep 12 |
| Carrots | Sow outdoors (spring) | Mar 23 – May 8 |
| Carrots | Sow outdoors (fall) | Jul 13 – Aug 28 |
| Garlic | Plant outdoors (fall) | Nov 12 – Dec 13 |
Where these dates come from
ZIP code 85619 is matched to the NOAA station Oracle 2 Se, AZ, 25.3 km away, at 4,510 ft elevation (261 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Oracle 2 Se, AZ (used) | 4,510 ft | Mar 23 | Nov 22 |
| Mt Lemmon Willow Canyon, AZ | 7,027 ft | Apr 1 | Nov 19 |
| Catalina Sp, AZ | 2,707 ft | Apr 2 | Nov 11 |
| Tucson Camp Ave Exp, AZ | 2,330 ft | Feb 20 | Nov 27 |
Frost dates near Mount Lemmon
- Tucson, AZ 85749 · last Feb 5, first Dec 9
- Catalina, AZ 85738 · last Apr 2, first Nov 11
- Oracle, AZ 85623 · last Mar 23, first Nov 22
- San Manuel, AZ 85631 · last Feb 4, first Dec 8
- Cortaro, AZ 85652 · last Feb 11, first Dec 2
- Marana, AZ 85658 · last Feb 11, first Dec 2
- Rillito, AZ 85654 · last Feb 11, first Dec 2
- Mammoth, AZ 85618 · last Mar 13, first Nov 19
Frequently asked questions
- When is the last frost in Mount Lemmon, AZ?
- For ZIP code 85619, the average last spring frost (32°F) is March 23, based on NOAA 1991-2020 climate normals for the Oracle 2 Se, AZ weather station. There is a 1-in-10 chance of a frost after April 16.
- When is the first frost in Mount Lemmon, AZ?
- The average first fall frost (32°F) is November 22. There is a 1-in-10 chance of frost by November 2, so tender plants are at risk from that point on.
- How long is the growing season in 85619?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 242 days long.
- Are these frost dates a forecast?
- No. They are 30-year averages and probabilities from NOAA weather station records. Use them to plan, then watch your local forecast before planting tender crops or leaving them uncovered.