Frost dates for 99003Chattaroy, WA
The average last spring frost in Chattaroy is May 22 and the average first fall frost is September 14, giving a typical growing season of about 112 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 22
- Average first fall frost
- Sep 14
- Growing season
- 112 days
Safer after Jun 15 (1-in-10 risk)
Possible by Aug 28 (1-in-10 risk)
Last frost typically in 208 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) | — | — | 72 days | 100% |
| Frost / freeze (32°F) | May 2 · May 22 · Jun 15 | Aug 28 · Sep 14 · Oct 1 | 112 days | 100% |
| Hard freeze (28°F) | Apr 18 · May 3 · May 21 | Sep 14 · Sep 29 · Oct 14 | 146 days | 100% |
Planting calendar for Chattaroy
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 21 – Jun 27 |
| Tomatoes | Transplant outdoors | Jun 7 – May 25 |
| Peppers | Start seeds indoors | Apr 21 – May 22 |
| Peppers | Transplant outdoors | Jun 21 – Jul 22 |
| Eggplant | Start seeds indoors | May 8 – Jun 6 |
| Eggplant | Transplant outdoors | Jun 21 – Jul 22 |
| Cucumbers | Sow outdoors | Jun 21 – Jun 4 |
| Summer squash | Sow outdoors | Jun 7 – Jul 22 |
| Winter squash & pumpkins | Sow outdoors | Jun 21 – Jul 22 |
| Snap beans | Sow outdoors | Jun 7 – Jun 27 |
| Sweet corn | Sow outdoors | Jun 7 – May 25 |
| Watermelon & cantaloupe | Sow outdoors | Jun 21 – Jul 22 |
| Okra | Sow outdoors | Jun 14 – Jul 7 |
| Peas | Sow outdoors (spring) | Apr 21 – Jun 6 |
| Potatoes | Plant outdoors (spring) | Apr 21 – Jun 21 |
| Onions | Start seeds indoors (spring) | Mar 10 – Apr 6 |
| Onions | Transplant outdoors (spring) | May 8 – Jun 6 |
| Broccoli | Start seeds indoors (spring) | Apr 3 – May 7 |
| Broccoli | Transplant outdoors (spring) | May 8 – Jun 6 |
| Broccoli | Start seeds indoors (fall) | May 15 – May 25 |
| Broccoli | Transplant outdoors (fall) | Jun 14 – Jun 25 |
| Cabbage | Start seeds indoors (spring) | Mar 24 – Apr 21 |
| Cabbage | Transplant outdoors (spring) | Apr 21 – May 22 |
| Cabbage | Start seeds indoors (fall) | May 5 – Jun 4 |
| Cabbage | Transplant outdoors (fall) | Jun 4 – Jul 5 |
| Leaf lettuce | Sow outdoors (spring) | Apr 21 – Jul 7 |
| Leaf lettuce | Sow outdoors (fall) | Jun 4 – Jul 21 |
| Spinach | Sow outdoors (spring) | Apr 14 – May 28 |
| Spinach | Sow outdoors (fall) | Jun 21 – Jul 26 |
| Radishes | Sow outdoors (spring) | Apr 21 – Jun 11 |
| Radishes | Sow outdoors (fall) | Jun 4 – Aug 5 |
| Kale | Sow outdoors (spring) | May 8 – May 28 |
| Kale | Sow outdoors (fall) | May 28 – Jul 5 |
| Carrots | Sow outdoors (spring) | May 22 – Jul 7 |
| Carrots | Sow outdoors (fall) | May 5 – Jun 20 |
| Garlic | Plant outdoors (fall) | Sep 4 – Oct 5 |
Where these dates come from
ZIP code 99003 is matched to the NOAA station Deer Park Ap, WA, 11.8 km away, at 2,191 ft elevation (85 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Deer Park Ap, WA (used) | 2,191 ft | May 22 | Sep 14 |
| Spokane Felts Fld, WA | 1,953 ft | Apr 26 | Oct 15 |
| Newport, WA | 2,162 ft | May 12 | Sep 21 |
| Spokane Wfo, WA | 2,392 ft | May 10 | Sep 26 |
Frost dates near Chattaroy
- Colbert, WA 99005 · last Apr 26, first Oct 15
- Elk, WA 99009 · last May 22, first Sep 14
- Mead, WA 99021 · last Apr 26, first Oct 15
- Deer Park, WA 99006 · last May 22, first Sep 14
- Spokane, WA 99217 · last Apr 26, first Oct 12
- Clayton, WA 99110 · last May 22, first Sep 14
- Blanchard, ID 83804 · last May 12, first Sep 21
- Nine Mile Falls, WA 99026 · last Apr 26, first Oct 15
Frequently asked questions
- When is the last frost in Chattaroy, WA?
- For ZIP code 99003, the average last spring frost (32°F) is May 22, based on NOAA 1991-2020 climate normals for the Deer Park Ap, WA weather station. There is a 1-in-10 chance of a frost after June 15.
- When is the first frost in Chattaroy, WA?
- The average first fall frost (32°F) is September 14. There is a 1-in-10 chance of frost by August 28, so tender plants are at risk from that point on.
- How long is the growing season in 99003?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 112 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.