Frost dates for 86046Williams, AZ
The average last spring frost in Williams is May 9 and the average first fall frost is October 19, giving a typical growing season of about 161 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 9
- Average first fall frost
- Oct 19
- Growing season
- 161 days
Safer after May 27 (1-in-10 risk)
Possible by Oct 3 (1-in-10 risk)
Last frost typically in 194 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) | May 8 · May 24 · Jun 6 | Sep 24 · Oct 6 · Oct 20 | 136 days | 100% |
| Frost / freeze (32°F) | Apr 24 · May 9 · May 27 | Oct 3 · Oct 19 · Nov 3 | 161 days | 100% |
| Hard freeze (28°F) | Apr 6 · Apr 24 · May 14 | Oct 14 · Oct 31 · Nov 13 | 188 days | 100% |
Planting calendar for Williams
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 | Apr 8 – Jun 14 |
| Tomatoes | Transplant outdoors | May 25 – Jun 29 |
| Peppers | Start seeds indoors | Apr 8 – May 9 |
| Peppers | Transplant outdoors | Jun 8 – Jul 9 |
| Eggplant | Start seeds indoors | Apr 25 – May 24 |
| Eggplant | Transplant outdoors | Jun 8 – Jul 9 |
| Cucumbers | Sow outdoors | Jun 8 – Jul 9 |
| Summer squash | Sow outdoors | May 25 – Jul 9 |
| Winter squash & pumpkins | Sow outdoors | Jun 8 – Jul 9 |
| Snap beans | Sow outdoors | May 25 – Aug 1 |
| Sweet corn | Sow outdoors | May 25 – Jun 29 |
| Watermelon & cantaloupe | Sow outdoors | Jun 8 – Jul 9 |
| Okra | Sow outdoors | Jun 1 – Jun 24 |
| Peas | Sow outdoors (spring) | Apr 8 – May 24 |
| Potatoes | Plant outdoors (spring) | Apr 8 – Jun 8 |
| Onions | Start seeds indoors (spring) | Feb 25 – Mar 24 |
| Onions | Transplant outdoors (spring) | Apr 25 – May 24 |
| Broccoli | Start seeds indoors (spring) | Mar 21 – Apr 24 |
| Broccoli | Transplant outdoors (spring) | Apr 25 – May 24 |
| Broccoli | Start seeds indoors (fall) | Jun 19 – Jun 29 |
| Broccoli | Transplant outdoors (fall) | Jul 19 – Jul 30 |
| Cabbage | Start seeds indoors (spring) | Mar 11 – Apr 8 |
| Cabbage | Transplant outdoors (spring) | Apr 8 – May 9 |
| Cabbage | Start seeds indoors (fall) | Jun 9 – Jul 9 |
| Cabbage | Transplant outdoors (fall) | Jul 9 – Aug 9 |
| Leaf lettuce | Sow outdoors (spring) | Apr 8 – Jun 24 |
| Leaf lettuce | Sow outdoors (fall) | Jul 9 – Aug 25 |
| Spinach | Sow outdoors (spring) | Apr 1 – May 15 |
| Spinach | Sow outdoors (fall) | Jul 26 – Aug 30 |
| Radishes | Sow outdoors (spring) | Apr 8 – May 29 |
| Radishes | Sow outdoors (fall) | Jul 9 – Sep 9 |
| Kale | Sow outdoors (spring) | Apr 25 – May 15 |
| Kale | Sow outdoors (fall) | Jul 2 – Aug 9 |
| Carrots | Sow outdoors (spring) | May 9 – Jun 24 |
| Carrots | Sow outdoors (fall) | Jun 9 – Jul 25 |
| Garlic | Plant outdoors (fall) | Oct 9 – Nov 9 |
Where these dates come from
ZIP code 86046 is matched to the NOAA station Williams 35 Nnw, AZ, 28 km away, at 5,990 ft elevation (152 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Williams 35 Nnw, AZ (used) | 5,990 ft | May 9 | Oct 19 |
| Williams, AZ | 6,909 ft | May 22 | Oct 5 |
| Grand Canyon Np Ap, AZ | 6,606 ft | Jun 17 | Sep 24 |
| Bellemont Wfo, AZ | 7,152 ft | Jun 21 | Sep 17 |
Frost dates near Williams
- Parks, AZ 86018 · last Jun 21, first Sep 17
- Grand Canyon, AZ 86023 · last Jun 17, first Sep 24
- Bellemont, AZ 86015 · last Jun 21, first Sep 17
- Ash Fork, AZ 86320 · last May 10, first Oct 15
- Gray Mountain, AZ 86016 · last Apr 7, first Nov 3
- Flagstaff, AZ 86002 · last Jun 4, first Sep 28
- Paulden, AZ 86334 · last May 24, first Oct 7
- North Rim, AZ 86052 · last Jun 3, first Sep 27
Frequently asked questions
- When is the last frost in Williams, AZ?
- For ZIP code 86046, the average last spring frost (32°F) is May 9, based on NOAA 1991-2020 climate normals for the Williams 35 Nnw, AZ weather station. There is a 1-in-10 chance of a frost after May 27.
- When is the first frost in Williams, AZ?
- The average first fall frost (32°F) is October 19. There is a 1-in-10 chance of frost by October 3, so tender plants are at risk from that point on.
- How long is the growing season in 86046?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 161 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.