Frost dates for 86435Supai, AZ
The average last spring frost in Supai is February 9 and the average first fall frost is December 5, giving a typical growing season of about 295 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Feb 9
- Average first fall frost
- Dec 5
- Growing season
- 295 days
Safer after Mar 4 (1-in-10 risk)
Possible by Nov 21 (1-in-10 risk)
First frost typically in 34 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 13 · Mar 3 · Mar 21 | Nov 11 · Nov 23 · Dec 6 | 263 days | 100% |
| Frost / freeze (32°F) | Jan 20 · Feb 9 · Mar 4 | Nov 21 · Dec 5 · Dec 23 | 295 days | 100% |
| Hard freeze (28°F) | Dec 27 · Jan 22 · Feb 14 | Dec 2 · Dec 20 · Jan 13 | 335 days | 90% |
Planting calendar for Supai
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 9 – Mar 17 |
| Tomatoes | Transplant outdoors | Feb 25 – Aug 15 |
| Peppers | Start seeds indoors | Jan 9 – Feb 9 |
| Peppers | Transplant outdoors | Mar 11 – Apr 11 |
| Eggplant | Start seeds indoors | Jan 26 – Feb 24 |
| Eggplant | Transplant outdoors | Mar 11 – Apr 11 |
| Cucumbers | Sow outdoors | Mar 11 – Aug 25 |
| Summer squash | Sow outdoors | Feb 25 – Apr 11 |
| Winter squash & pumpkins | Sow outdoors | Mar 11 – Apr 11 |
| Snap beans | Sow outdoors | Feb 25 – Sep 17 |
| Sweet corn | Sow outdoors | Feb 25 – Aug 15 |
| Watermelon & cantaloupe | Sow outdoors | Mar 11 – Apr 11 |
| Okra | Sow outdoors | Mar 4 – Mar 27 |
| Peas | Sow outdoors (spring) | Jan 9 – Feb 24 |
| Potatoes | Plant outdoors (spring) | Jan 9 – Mar 11 |
| Onions | Start seeds indoors (spring) | Nov 28 – Dec 25 |
| Onions | Transplant outdoors (spring) | Jan 26 – Feb 24 |
| Broccoli | Start seeds indoors (spring) | Dec 22 – Jan 25 |
| Broccoli | Transplant outdoors (spring) | Jan 26 – Feb 24 |
| Broccoli | Start seeds indoors (fall) | Aug 5 – Aug 15 |
| Broccoli | Transplant outdoors (fall) | Sep 4 – Sep 15 |
| Cabbage | Start seeds indoors (spring) | Dec 12 – Jan 9 |
| Cabbage | Transplant outdoors (spring) | Jan 9 – Feb 9 |
| Cabbage | Start seeds indoors (fall) | Jul 26 – Aug 25 |
| Cabbage | Transplant outdoors (fall) | Aug 25 – Sep 25 |
| Leaf lettuce | Sow outdoors (spring) | Jan 9 – Mar 27 |
| Leaf lettuce | Sow outdoors (fall) | Aug 25 – Oct 11 |
| Spinach | Sow outdoors (spring) | Jan 2 – Feb 15 |
| Spinach | Sow outdoors (fall) | Sep 11 – Oct 16 |
| Radishes | Sow outdoors (spring) | Jan 9 – Mar 1 |
| Radishes | Sow outdoors (fall) | Aug 25 – Oct 26 |
| Kale | Sow outdoors (spring) | Jan 26 – Feb 15 |
| Kale | Sow outdoors (fall) | Aug 18 – Sep 25 |
| Carrots | Sow outdoors (spring) | Feb 9 – Mar 27 |
| Carrots | Sow outdoors (fall) | Jul 26 – Sep 10 |
| Garlic | Plant outdoors (fall) | Nov 25 – Dec 26 |
Where these dates come from
ZIP code 86435 is matched to the NOAA station Phantom Rch, AZ, 55.3 km away, at 2,530 ft elevation (758 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Phantom Rch, AZ (used) | 2,530 ft | Feb 9 | Dec 5 |
| Grand Canyon Np 2, AZ | 6,785 ft | Jun 1 | Oct 3 |
| Grand Canyon Visitor Ctr, AZ | 7,083 ft | May 2 | Oct 27 |
| Bright Angel Rs, AZ | 8,000 ft | Jun 3 | Sep 27 |
Frost dates near Supai
- North Rim, AZ 86052 · last Jun 3, first Sep 27
- Grand Canyon, AZ 86023 · last Jun 17, first Sep 24
- Fredonia, AZ 86022 · last Apr 29, first Oct 22
- Colorado City, AZ 86021 · last Apr 26, first Oct 25
- Williams, AZ 86046 · last May 9, first Oct 19
- Hildale, UT 84784 · last Apr 26, first Oct 25
- Kanab, UT 84741 · last Apr 29, first Oct 22
- Marble Canyon, AZ 86036 · last Jun 3, first Sep 27
Frequently asked questions
- When is the last frost in Supai, AZ?
- For ZIP code 86435, the average last spring frost (32°F) is February 9, based on NOAA 1991-2020 climate normals for the Phantom Rch, AZ weather station. There is a 1-in-10 chance of a frost after March 4.
- When is the first frost in Supai, AZ?
- The average first fall frost (32°F) is December 5. There is a 1-in-10 chance of frost by November 21, so tender plants are at risk from that point on.
- How long is the growing season in 86435?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 295 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.