Frost dates for 85652Cortaro, AZ
The average last spring frost in Cortaro is February 11 and the average first fall frost is December 2, giving a typical growing season of about 293 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Feb 11
- Average first fall frost
- Dec 2
- Growing season
- 293 days
Safer after Mar 7 (1-in-10 risk)
Possible by Nov 16 (1-in-10 risk)
First frost typically in 36 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 12 · Mar 6 · Mar 30 | Nov 4 · Nov 22 · Dec 6 | 257 days | 100% |
| Frost / freeze (32°F) | Jan 16 · Feb 11 · Mar 7 | Nov 16 · Dec 2 · Dec 20 | 293 days | 100% |
| Hard freeze (28°F) | Dec 21 · Jan 18 · Feb 17 | Nov 29 · Dec 15 · Jan 17 | 336 days | 91% |
Planting calendar for Cortaro
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 11 – Mar 19 |
| Tomatoes | Transplant outdoors | Feb 27 – Aug 12 |
| Peppers | Start seeds indoors | Jan 11 – Feb 11 |
| Peppers | Transplant outdoors | Mar 13 – Apr 13 |
| Eggplant | Start seeds indoors | Jan 28 – Feb 26 |
| Eggplant | Transplant outdoors | Mar 13 – Apr 13 |
| Cucumbers | Sow outdoors | Mar 13 – Aug 22 |
| Summer squash | Sow outdoors | Feb 27 – Apr 13 |
| Winter squash & pumpkins | Sow outdoors | Mar 13 – Apr 13 |
| Snap beans | Sow outdoors | Feb 27 – Sep 14 |
| Sweet corn | Sow outdoors | Feb 27 – Aug 12 |
| Watermelon & cantaloupe | Sow outdoors | Mar 13 – Apr 13 |
| Okra | Sow outdoors | Mar 6 – Mar 29 |
| Peas | Sow outdoors (spring) | Jan 11 – Feb 26 |
| Potatoes | Plant outdoors (spring) | Jan 11 – Mar 13 |
| Onions | Start seeds indoors (spring) | Nov 30 – Dec 27 |
| Onions | Transplant outdoors (spring) | Jan 28 – Feb 26 |
| Broccoli | Start seeds indoors (spring) | Dec 24 – Jan 27 |
| Broccoli | Transplant outdoors (spring) | Jan 28 – Feb 26 |
| Broccoli | Start seeds indoors (fall) | Aug 2 – Aug 12 |
| Broccoli | Transplant outdoors (fall) | Sep 1 – Sep 12 |
| Cabbage | Start seeds indoors (spring) | Dec 14 – Jan 11 |
| Cabbage | Transplant outdoors (spring) | Jan 11 – Feb 11 |
| Cabbage | Start seeds indoors (fall) | Jul 23 – Aug 22 |
| Cabbage | Transplant outdoors (fall) | Aug 22 – Sep 22 |
| Leaf lettuce | Sow outdoors (spring) | Jan 11 – Mar 29 |
| Leaf lettuce | Sow outdoors (fall) | Aug 22 – Oct 8 |
| Spinach | Sow outdoors (spring) | Jan 4 – Feb 17 |
| Spinach | Sow outdoors (fall) | Sep 8 – Oct 13 |
| Radishes | Sow outdoors (spring) | Jan 11 – Mar 3 |
| Radishes | Sow outdoors (fall) | Aug 22 – Oct 23 |
| Kale | Sow outdoors (spring) | Jan 28 – Feb 17 |
| Kale | Sow outdoors (fall) | Aug 15 – Sep 22 |
| Carrots | Sow outdoors (spring) | Feb 11 – Mar 29 |
| Carrots | Sow outdoors (fall) | Jul 23 – Sep 7 |
| Garlic | Plant outdoors (fall) | Nov 22 – Dec 23 |
Where these dates come from
ZIP code 85652 is matched to the NOAA station Tucson U Of A #1, AZ, 20.7 km away, at 2,315 ft elevation (45 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Tucson U Of A #1, AZ (used) | 2,315 ft | Feb 11 | Dec 2 |
| Tohono Chul, AZ | 2,527 ft | Feb 26 | Dec 4 |
| Catalina Sp, AZ | 2,707 ft | Apr 2 | Nov 11 |
| Tucson 17 Nw, AZ | 2,561 ft | Feb 23 | Dec 6 |
Frost dates near Cortaro
- Marana, AZ 85658 · last Feb 11, first Dec 2
- Rillito, AZ 85654 · last Feb 11, first Dec 2
- Tucson, AZ 85742 · last Feb 23, first Dec 6
- Catalina, AZ 85738 · last Apr 2, first Nov 11
- Red Rock, AZ 85145 · last Feb 6, first Dec 9
- Mount Lemmon, AZ 85619 · last Mar 23, first Nov 22
- Oracle, AZ 85623 · last Mar 23, first Nov 22
- Picacho, AZ 85141 · last Feb 6, first Dec 9
Frequently asked questions
- When is the last frost in Cortaro, AZ?
- For ZIP code 85652, the average last spring frost (32°F) is February 11, based on NOAA 1991-2020 climate normals for the Tucson U Of A #1, AZ weather station. There is a 1-in-10 chance of a frost after March 7.
- When is the first frost in Cortaro, AZ?
- The average first fall frost (32°F) is December 2. There is a 1-in-10 chance of frost by November 16, so tender plants are at risk from that point on.
- How long is the growing season in 85652?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 293 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.