Frost dates for 85144San Tan Valley, AZ
The average last spring frost in San Tan Valley is February 17 and the average first fall frost is November 29, giving a typical growing season of about 284 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Feb 17
- Average first fall frost
- Nov 29
- Growing season
- 284 days
Safer after Mar 8 (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) | Feb 16 · Mar 8 · Apr 5 | Nov 4 · Nov 19 · Dec 3 | 251 days | 100% |
| Frost / freeze (32°F) | Jan 22 · Feb 17 · Mar 8 | Nov 12 · Nov 29 · Dec 15 | 284 days | 100% |
| Hard freeze (28°F) | Dec 26 · Jan 26 · Feb 23 | Nov 23 · Dec 12 · Jan 6 | 322 days | 95% |
Planting calendar for San Tan Valley
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 17 – Mar 25 |
| Tomatoes | Transplant outdoors | Mar 5 – Aug 9 |
| Peppers | Start seeds indoors | Jan 17 – Feb 17 |
| Peppers | Transplant outdoors | Mar 19 – Apr 19 |
| Eggplant | Start seeds indoors | Feb 3 – Mar 4 |
| Eggplant | Transplant outdoors | Mar 19 – Apr 19 |
| Cucumbers | Sow outdoors | Mar 19 – Aug 19 |
| Summer squash | Sow outdoors | Mar 5 – Apr 19 |
| Winter squash & pumpkins | Sow outdoors | Mar 19 – Apr 19 |
| Snap beans | Sow outdoors | Mar 5 – Sep 11 |
| Sweet corn | Sow outdoors | Mar 5 – Aug 9 |
| Watermelon & cantaloupe | Sow outdoors | Mar 19 – Apr 19 |
| Okra | Sow outdoors | Mar 12 – Apr 4 |
| Peas | Sow outdoors (spring) | Jan 17 – Mar 4 |
| Potatoes | Plant outdoors (spring) | Jan 17 – Mar 19 |
| Onions | Start seeds indoors (spring) | Dec 6 – Jan 2 |
| Onions | Transplant outdoors (spring) | Feb 3 – Mar 4 |
| Broccoli | Start seeds indoors (spring) | Dec 30 – Feb 2 |
| Broccoli | Transplant outdoors (spring) | Feb 3 – Mar 4 |
| Broccoli | Start seeds indoors (fall) | Jul 30 – Aug 9 |
| Broccoli | Transplant outdoors (fall) | Aug 29 – Sep 9 |
| Cabbage | Start seeds indoors (spring) | Dec 20 – Jan 17 |
| Cabbage | Transplant outdoors (spring) | Jan 17 – Feb 17 |
| Cabbage | Start seeds indoors (fall) | Jul 20 – Aug 19 |
| Cabbage | Transplant outdoors (fall) | Aug 19 – Sep 19 |
| Leaf lettuce | Sow outdoors (spring) | Jan 17 – Apr 4 |
| Leaf lettuce | Sow outdoors (fall) | Aug 19 – Oct 5 |
| Spinach | Sow outdoors (spring) | Jan 10 – Feb 23 |
| Spinach | Sow outdoors (fall) | Sep 5 – Oct 10 |
| Radishes | Sow outdoors (spring) | Jan 17 – Mar 9 |
| Radishes | Sow outdoors (fall) | Aug 19 – Oct 20 |
| Kale | Sow outdoors (spring) | Feb 3 – Feb 23 |
| Kale | Sow outdoors (fall) | Aug 12 – Sep 19 |
| Carrots | Sow outdoors (spring) | Feb 17 – Apr 4 |
| Carrots | Sow outdoors (fall) | Jul 20 – Sep 4 |
| Garlic | Plant outdoors (fall) | Nov 19 – Dec 20 |
Where these dates come from
ZIP code 85144 is matched to the NOAA station Casa Grande Nm, AZ, 21.9 km away, at 1,419 ft elevation (103 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Casa Grande Nm, AZ (used) | 1,419 ft | Feb 17 | Nov 29 |
| Chandler Heights, AZ | 1,425 ft | Feb 1 | Dec 11 |
| Florence, AZ | 1,400 ft | Jan 30 | Dec 12 |
| E Mesa, AZ | 1,518 ft | Feb 1 | Dec 10 |
Frost dates near San Tan Valley
- San Tan Valley, AZ 85140 · last Feb 17, first Nov 29
- Queen Creek, AZ 85142 · last Feb 1, first Dec 11
- Chandler Heights, AZ 85127 · last Feb 1, first Dec 11
- Gilbert, AZ 85298 · last Feb 1, first Dec 11
- Mesa, AZ 85212 · last Feb 1, first Dec 10
- Higley, AZ 85236 · last Feb 1, first Dec 10
- Sacaton, AZ 85147 · last Feb 17, first Nov 29
- Gold Canyon, AZ 85118 · last Feb 11, first Dec 10
Frequently asked questions
- When is the last frost in San Tan Valley, AZ?
- For ZIP code 85144, the average last spring frost (32°F) is February 17, based on NOAA 1991-2020 climate normals for the Casa Grande Nm, AZ weather station. There is a 1-in-10 chance of a frost after March 8.
- When is the first frost in San Tan Valley, 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 85144?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 284 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.