Frost dates for 99109Chewelah, WA
The average last spring frost in Chewelah is May 16 and the average first fall frost is September 15, giving a typical growing season of about 120 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 16
- Average first fall frost
- Sep 15
- Growing season
- 120 days
Safer after Jun 7 (1-in-10 risk)
Possible by Sep 1 (1-in-10 risk)
Last frost typically in 203 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) | — | — | 79 days | 100% |
| Frost / freeze (32°F) | Apr 30 · May 16 · Jun 7 | Sep 1 · Sep 15 · Sep 29 | 120 days | 100% |
| Hard freeze (28°F) | Apr 12 · Apr 30 · May 14 | Sep 15 · Sep 28 · Oct 13 | 153 days | 100% |
Planting calendar for Chewelah
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 15 – Jun 21 |
| Tomatoes | Transplant outdoors | Jun 1 – May 26 |
| Peppers | Start seeds indoors | Apr 15 – May 16 |
| Peppers | Transplant outdoors | Jun 15 – Jul 16 |
| Eggplant | Start seeds indoors | May 2 – May 31 |
| Eggplant | Transplant outdoors | Jun 15 – Jul 16 |
| Cucumbers | Sow outdoors | Jun 15 – Jun 5 |
| Summer squash | Sow outdoors | Jun 1 – Jul 16 |
| Winter squash & pumpkins | Sow outdoors | Jun 15 – Jul 16 |
| Snap beans | Sow outdoors | Jun 1 – Jun 28 |
| Sweet corn | Sow outdoors | Jun 1 – May 26 |
| Watermelon & cantaloupe | Sow outdoors | Jun 15 – Jul 16 |
| Okra | Sow outdoors | Jun 8 – Jul 1 |
| Peas | Sow outdoors (spring) | Apr 15 – May 31 |
| Potatoes | Plant outdoors (spring) | Apr 15 – Jun 15 |
| Onions | Start seeds indoors (spring) | Mar 4 – Mar 31 |
| Onions | Transplant outdoors (spring) | May 2 – May 31 |
| Broccoli | Start seeds indoors (spring) | Mar 28 – May 1 |
| Broccoli | Transplant outdoors (spring) | May 2 – May 31 |
| Broccoli | Start seeds indoors (fall) | May 16 – May 26 |
| Broccoli | Transplant outdoors (fall) | Jun 15 – Jun 26 |
| Cabbage | Start seeds indoors (spring) | Mar 18 – Apr 15 |
| Cabbage | Transplant outdoors (spring) | Apr 15 – May 16 |
| Cabbage | Start seeds indoors (fall) | May 6 – Jun 5 |
| Cabbage | Transplant outdoors (fall) | Jun 5 – Jul 6 |
| Leaf lettuce | Sow outdoors (spring) | Apr 15 – Jul 1 |
| Leaf lettuce | Sow outdoors (fall) | Jun 5 – Jul 22 |
| Spinach | Sow outdoors (spring) | Apr 8 – May 22 |
| Spinach | Sow outdoors (fall) | Jun 22 – Jul 27 |
| Radishes | Sow outdoors (spring) | Apr 15 – Jun 5 |
| Radishes | Sow outdoors (fall) | Jun 5 – Aug 6 |
| Kale | Sow outdoors (spring) | May 2 – May 22 |
| Kale | Sow outdoors (fall) | May 29 – Jul 6 |
| Carrots | Sow outdoors (spring) | May 16 – Jul 1 |
| Carrots | Sow outdoors (fall) | May 6 – Jun 21 |
| Garlic | Plant outdoors (fall) | Sep 5 – Oct 6 |
Where these dates come from
ZIP code 99109 is matched to the NOAA station Chewelah, WA, 3 km away, at 1,670 ft elevation (23 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Chewelah, WA (used) | 1,670 ft | May 16 | Sep 15 |
| Colville, WA | 1,554 ft | May 2 | Oct 2 |
| Deer Park Ap, WA | 2,191 ft | May 22 | Sep 14 |
| Newport, WA | 2,162 ft | May 12 | Sep 21 |
Frost dates near Chewelah
- Addy, WA 99101 · last May 16, first Sep 15
- Valley, WA 99181 · last May 16, first Sep 15
- Gifford, WA 99131 · last May 16, first Sep 15
- Loon Lake, WA 99148 · last May 22, first Sep 14
- Rice, WA 99167 · last May 30, first Sep 10
- Springdale, WA 99173 · last May 10, first Sep 26
- Hunters, WA 99137 · last Jun 6, first Sep 11
- Colville, WA 99114 · last May 2, first Oct 2
Frequently asked questions
- When is the last frost in Chewelah, WA?
- For ZIP code 99109, the average last spring frost (32°F) is May 16, based on NOAA 1991-2020 climate normals for the Chewelah, WA weather station. There is a 1-in-10 chance of a frost after June 7.
- When is the first frost in Chewelah, WA?
- The average first fall frost (32°F) is September 15. There is a 1-in-10 chance of frost by September 1, so tender plants are at risk from that point on.
- How long is the growing season in 99109?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 120 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.