Frost dates for 98855Tonasket, WA
The average last spring frost in Tonasket is April 30 and the average first fall frost is October 7, giving a typical growing season of about 160 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Apr 30
- Average first fall frost
- Oct 7
- Growing season
- 160 days
Safer after May 15 (1-in-10 risk)
Possible by Sep 23 (1-in-10 risk)
Last frost typically in 186 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) | Apr 28 · May 13 · Jun 1 | Sep 12 · Sep 28 · Oct 11 | 136 days | 100% |
| Frost / freeze (32°F) | Apr 14 · Apr 30 · May 15 | Sep 23 · Oct 7 · Oct 22 | 160 days | 100% |
| Hard freeze (28°F) | Mar 26 · Apr 14 · May 2 | Oct 3 · Oct 19 · Nov 4 | 188 days | 100% |
Planting calendar for Tonasket
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 | Mar 30 – Jun 5 |
| Tomatoes | Transplant outdoors | May 16 – Jun 17 |
| Peppers | Start seeds indoors | Mar 30 – Apr 30 |
| Peppers | Transplant outdoors | May 30 – Jun 30 |
| Eggplant | Start seeds indoors | Apr 16 – May 15 |
| Eggplant | Transplant outdoors | May 30 – Jun 30 |
| Cucumbers | Sow outdoors | May 30 – Jun 27 |
| Summer squash | Sow outdoors | May 16 – Jun 30 |
| Winter squash & pumpkins | Sow outdoors | May 30 – Jun 30 |
| Snap beans | Sow outdoors | May 16 – Jul 20 |
| Sweet corn | Sow outdoors | May 16 – Jun 17 |
| Watermelon & cantaloupe | Sow outdoors | May 30 – Jun 30 |
| Okra | Sow outdoors | May 23 – Jun 15 |
| Peas | Sow outdoors (spring) | Mar 30 – May 15 |
| Potatoes | Plant outdoors (spring) | Mar 30 – May 30 |
| Onions | Start seeds indoors (spring) | Feb 16 – Mar 15 |
| Onions | Transplant outdoors (spring) | Apr 16 – May 15 |
| Broccoli | Start seeds indoors (spring) | Mar 12 – Apr 15 |
| Broccoli | Transplant outdoors (spring) | Apr 16 – May 15 |
| Broccoli | Start seeds indoors (fall) | Jun 7 – Jun 17 |
| Broccoli | Transplant outdoors (fall) | Jul 7 – Jul 18 |
| Cabbage | Start seeds indoors (spring) | Mar 2 – Mar 30 |
| Cabbage | Transplant outdoors (spring) | Mar 30 – Apr 30 |
| Cabbage | Start seeds indoors (fall) | May 28 – Jun 27 |
| Cabbage | Transplant outdoors (fall) | Jun 27 – Jul 28 |
| Leaf lettuce | Sow outdoors (spring) | Mar 30 – Jun 15 |
| Leaf lettuce | Sow outdoors (fall) | Jun 27 – Aug 13 |
| Spinach | Sow outdoors (spring) | Mar 23 – May 6 |
| Spinach | Sow outdoors (fall) | Jul 14 – Aug 18 |
| Radishes | Sow outdoors (spring) | Mar 30 – May 20 |
| Radishes | Sow outdoors (fall) | Jun 27 – Aug 28 |
| Kale | Sow outdoors (spring) | Apr 16 – May 6 |
| Kale | Sow outdoors (fall) | Jun 20 – Jul 28 |
| Carrots | Sow outdoors (spring) | Apr 30 – Jun 15 |
| Carrots | Sow outdoors (fall) | May 28 – Jul 13 |
| Garlic | Plant outdoors (fall) | Sep 27 – Oct 28 |
Where these dates come from
ZIP code 98855 is matched to the NOAA station Omak Ap, WA, 30.1 km away, at 1,296 ft elevation (364 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Omak Ap, WA (used) | 1,296 ft | Apr 30 | Oct 7 |
| Tonasket 4 Nne, WA | 960 ft | Apr 26 | Oct 10 |
| Tonasket 11Ne, WA | 3,434 ft | May 6 | Oct 6 |
| Republic, WA | 2,555 ft | May 30 | Sep 10 |
Frost dates near Tonasket
- Oroville, WA 98844 · last Apr 26, first Oct 10
- Loomis, WA 98827 · last Apr 26, first Oct 10
- Riverside, WA 98849 · last Apr 30, first Oct 7
- Conconully, WA 98819 · last May 9, first Sep 29
- Wauconda, WA 98859 · last May 6, first Oct 6
- Omak, WA 98841 · last Apr 30, first Oct 7
- Okanogan, WA 98840 · last Apr 30, first Oct 7
- Republic, WA 99166 · last May 30, first Sep 10
Frequently asked questions
- When is the last frost in Tonasket, WA?
- For ZIP code 98855, the average last spring frost (32°F) is April 30, based on NOAA 1991-2020 climate normals for the Omak Ap, WA weather station. There is a 1-in-10 chance of a frost after May 15.
- When is the first frost in Tonasket, WA?
- The average first fall frost (32°F) is October 7. There is a 1-in-10 chance of frost by September 23, so tender plants are at risk from that point on.
- How long is the growing season in 98855?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 160 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.