Frost dates for 85742Tucson, AZ
The average last spring frost in Tucson is February 23 and the average first fall frost is December 6, giving a typical growing season of about 287 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Feb 23
- Average first fall frost
- Dec 6
- Growing season
- 287 days
Safer after Mar 22 (1-in-10 risk)
Possible by Nov 18 (1-in-10 risk)
First frost typically in 41 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) | Feb 22 · Mar 15 · Apr 10 | Nov 7 · Nov 24 · Dec 10 | 252 days | 100% |
| Frost / freeze (32°F) | Jan 15 · Feb 23 · Mar 22 | Nov 18 · Dec 6 · Dec 25 | 287 days | 100% |
| Hard freeze (28°F) | Dec 19 · Jan 22 · Mar 1 | Nov 30 · Dec 19 · Jan 22 | 333 days | 87% |
Planting calendar for Tucson
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 | Jan 23 – Mar 31 |
| Tomatoes | Transplant outdoors | Mar 11 – Aug 16 |
| Peppers | Start seeds indoors | Jan 23 – Feb 23 |
| Peppers | Transplant outdoors | Mar 25 – Apr 25 |
| Eggplant | Start seeds indoors | Feb 9 – Mar 10 |
| Eggplant | Transplant outdoors | Mar 25 – Apr 25 |
| Cucumbers | Sow outdoors | Mar 25 – Aug 26 |
| Summer squash | Sow outdoors | Mar 11 – Apr 25 |
| Winter squash & pumpkins | Sow outdoors | Mar 25 – Apr 25 |
| Snap beans | Sow outdoors | Mar 11 – Sep 18 |
| Sweet corn | Sow outdoors | Mar 11 – Aug 16 |
| Watermelon & cantaloupe | Sow outdoors | Mar 25 – Apr 25 |
| Okra | Sow outdoors | Mar 18 – Apr 10 |
| Peas | Sow outdoors (spring) | Jan 23 – Mar 10 |
| Potatoes | Plant outdoors (spring) | Jan 23 – Mar 25 |
| Onions | Start seeds indoors (spring) | Dec 12 – Jan 8 |
| Onions | Transplant outdoors (spring) | Feb 9 – Mar 10 |
| Broccoli | Start seeds indoors (spring) | Jan 5 – Feb 8 |
| Broccoli | Transplant outdoors (spring) | Feb 9 – Mar 10 |
| Broccoli | Start seeds indoors (fall) | Aug 6 – Aug 16 |
| Broccoli | Transplant outdoors (fall) | Sep 5 – Sep 16 |
| Cabbage | Start seeds indoors (spring) | Dec 26 – Jan 23 |
| Cabbage | Transplant outdoors (spring) | Jan 23 – Feb 23 |
| Cabbage | Start seeds indoors (fall) | Jul 27 – Aug 26 |
| Cabbage | Transplant outdoors (fall) | Aug 26 – Sep 26 |
| Leaf lettuce | Sow outdoors (spring) | Jan 23 – Apr 10 |
| Leaf lettuce | Sow outdoors (fall) | Aug 26 – Oct 12 |
| Spinach | Sow outdoors (spring) | Jan 16 – Mar 1 |
| Spinach | Sow outdoors (fall) | Sep 12 – Oct 17 |
| Radishes | Sow outdoors (spring) | Jan 23 – Mar 15 |
| Radishes | Sow outdoors (fall) | Aug 26 – Oct 27 |
| Kale | Sow outdoors (spring) | Feb 9 – Mar 1 |
| Kale | Sow outdoors (fall) | Aug 19 – Sep 26 |
| Carrots | Sow outdoors (spring) | Feb 23 – Apr 10 |
| Carrots | Sow outdoors (fall) | Jul 27 – Sep 11 |
| Garlic | Plant outdoors (fall) | Nov 26 – Dec 27 |
Where these dates come from
ZIP code 85742 is matched to the NOAA station Tucson 17 Nw, AZ, 21 km away, at 2,561 ft elevation (45 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Tucson 17 Nw, AZ (used) | 2,561 ft | Feb 23 | Dec 6 |
| Tohono Chul, AZ | 2,527 ft | Feb 26 | Dec 4 |
| Catalina Sp, AZ | 2,707 ft | Apr 2 | Nov 11 |
| Tucson U Of A #1, AZ | 2,315 ft | Feb 11 | Dec 2 |
Frost dates near Tucson
- Cortaro, AZ 85652 · last Feb 11, first Dec 2
- Tucson, AZ 85741 · last Feb 11, first Dec 2
- Marana, AZ 85658 · last Feb 11, first Dec 2
- Rillito, AZ 85654 · last Feb 11, first Dec 2
- Catalina, AZ 85738 · last Apr 2, first Nov 11
- Mount Lemmon, AZ 85619 · last Mar 23, first Nov 22
- Red Rock, AZ 85145 · last Feb 6, first Dec 9
- Oracle, AZ 85623 · last Mar 23, first Nov 22
Frequently asked questions
- When is the last frost in Tucson, AZ?
- For ZIP code 85742, the average last spring frost (32°F) is February 23, based on NOAA 1991-2020 climate normals for the Tucson 17 Nw, AZ weather station. There is a 1-in-10 chance of a frost after March 22.
- When is the first frost in Tucson, AZ?
- The average first fall frost (32°F) is December 6. There is a 1-in-10 chance of frost by November 18, so tender plants are at risk from that point on.
- How long is the growing season in 85742?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 287 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.