Frost dates for 85638Tombstone, AZ
The average last spring frost in Tombstone is March 4 and the average first fall frost is November 29, giving a typical growing season of about 264 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Mar 4
- Average first fall frost
- Nov 29
- Growing season
- 264 days
Safer after Mar 31 (1-in-10 risk)
Possible by Nov 12 (1-in-10 risk)
First frost typically in 33 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 5 · Mar 29 · Apr 18 | Oct 31 · Nov 17 · Dec 3 | 231 days | 100% |
| Frost / freeze (32°F) | Feb 3 · Mar 4 · Mar 31 | Nov 12 · Nov 29 · Dec 17 | 264 days | 100% |
| Hard freeze (28°F) | Jan 5 · Feb 8 · Mar 10 | Nov 23 · Dec 12 · Jan 10 | 305 days | 99% |
Planting calendar for Tombstone
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 1 – Apr 9 |
| Tomatoes | Transplant outdoors | Mar 20 – Aug 9 |
| Peppers | Start seeds indoors | Feb 1 – Mar 4 |
| Peppers | Transplant outdoors | Apr 3 – May 4 |
| Eggplant | Start seeds indoors | Feb 18 – Mar 19 |
| Eggplant | Transplant outdoors | Apr 3 – May 4 |
| Cucumbers | Sow outdoors | Apr 3 – Aug 19 |
| Summer squash | Sow outdoors | Mar 20 – May 4 |
| Winter squash & pumpkins | Sow outdoors | Apr 3 – May 4 |
| Snap beans | Sow outdoors | Mar 20 – Sep 11 |
| Sweet corn | Sow outdoors | Mar 20 – Aug 9 |
| Watermelon & cantaloupe | Sow outdoors | Apr 3 – May 4 |
| Okra | Sow outdoors | Mar 27 – Apr 19 |
| Peas | Sow outdoors (spring) | Feb 1 – Mar 19 |
| Potatoes | Plant outdoors (spring) | Feb 1 – Apr 3 |
| Onions | Start seeds indoors (spring) | Dec 21 – Jan 17 |
| Onions | Transplant outdoors (spring) | Feb 18 – Mar 19 |
| Broccoli | Start seeds indoors (spring) | Jan 14 – Feb 17 |
| Broccoli | Transplant outdoors (spring) | Feb 18 – Mar 19 |
| Broccoli | Start seeds indoors (fall) | Jul 30 – Aug 9 |
| Broccoli | Transplant outdoors (fall) | Aug 29 – Sep 9 |
| Cabbage | Start seeds indoors (spring) | Jan 4 – Feb 1 |
| Cabbage | Transplant outdoors (spring) | Feb 1 – Mar 4 |
| Cabbage | Start seeds indoors (fall) | Jul 20 – Aug 19 |
| Cabbage | Transplant outdoors (fall) | Aug 19 – Sep 19 |
| Leaf lettuce | Sow outdoors (spring) | Feb 1 – Apr 19 |
| Leaf lettuce | Sow outdoors (fall) | Aug 19 – Oct 5 |
| Spinach | Sow outdoors (spring) | Jan 25 – Mar 10 |
| Spinach | Sow outdoors (fall) | Sep 5 – Oct 10 |
| Radishes | Sow outdoors (spring) | Feb 1 – Mar 24 |
| Radishes | Sow outdoors (fall) | Aug 19 – Oct 20 |
| Kale | Sow outdoors (spring) | Feb 18 – Mar 10 |
| Kale | Sow outdoors (fall) | Aug 12 – Sep 19 |
| Carrots | Sow outdoors (spring) | Mar 4 – Apr 19 |
| Carrots | Sow outdoors (fall) | Jul 20 – Sep 4 |
| Garlic | Plant outdoors (fall) | Nov 19 – Dec 20 |
Where these dates come from
ZIP code 85638 is matched to the NOAA station Tombstone, AZ, 1.4 km away, at 4,659 ft elevation (207 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Tombstone, AZ (used) | 4,659 ft | Mar 4 | Nov 29 |
| Benson 6Se, AZ | 3,690 ft | Apr 12 | Nov 1 |
| Sierra Vista, AZ | 4,606 ft | Apr 5 | Nov 9 |
| Kartchner Caverns, AZ | 4,690 ft | Mar 20 | Nov 15 |
Frost dates near Tombstone
- Sierra Vista, AZ 85636 · last Apr 5, first Nov 9
- Saint David, AZ 85630 · last Apr 12, first Nov 1
- Huachuca City, AZ 85616 · last Apr 5, first Nov 9
- Mc Neal, AZ 85617 · last Mar 4, first Nov 29
- Fort Huachuca, AZ 85613 · last Apr 5, first Nov 9
- Dragoon, AZ 85609 · last Apr 14, first Nov 2
- Benson, AZ 85602 · last Apr 12, first Nov 1
- Bisbee, AZ 85603 · last Apr 1, first Nov 10
Frequently asked questions
- When is the last frost in Tombstone, AZ?
- For ZIP code 85638, the average last spring frost (32°F) is March 4, based on NOAA 1991-2020 climate normals for the Tombstone, AZ weather station. There is a 1-in-10 chance of a frost after March 31.
- When is the first frost in Tombstone, AZ?
- The average first fall frost (32°F) is November 29. There is a 1-in-10 chance of frost by November 12, so tender plants are at risk from that point on.
- How long is the growing season in 85638?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 264 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.