Frost dates for 98844Oroville, WA
The average last spring frost in Oroville is April 26 and the average first fall frost is October 10, giving a typical growing season of about 168 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Apr 26
- Average first fall frost
- Oct 10
- Growing season
- 168 days
Safer after May 11 (1-in-10 risk)
Possible by Sep 28 (1-in-10 risk)
Last frost typically in 182 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 27 · May 11 · May 29 | Sep 15 · Sep 29 · Oct 12 | 140 days | 100% |
| Frost / freeze (32°F) | Apr 6 · Apr 26 · May 11 | Sep 28 · Oct 10 · Oct 25 | 168 days | 100% |
| Hard freeze (28°F) | Mar 14 · Apr 1 · Apr 20 | Oct 7 · Oct 23 · Nov 7 | 203 days | 100% |
Planting calendar for Oroville
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 26 – Jun 1 |
| Tomatoes | Transplant outdoors | May 12 – Jun 20 |
| Peppers | Start seeds indoors | Mar 26 – Apr 26 |
| Peppers | Transplant outdoors | May 26 – Jun 26 |
| Eggplant | Start seeds indoors | Apr 12 – May 11 |
| Eggplant | Transplant outdoors | May 26 – Jun 26 |
| Cucumbers | Sow outdoors | May 26 – Jun 30 |
| Summer squash | Sow outdoors | May 12 – Jun 26 |
| Winter squash & pumpkins | Sow outdoors | May 26 – Jun 26 |
| Snap beans | Sow outdoors | May 12 – Jul 23 |
| Sweet corn | Sow outdoors | May 12 – Jun 20 |
| Watermelon & cantaloupe | Sow outdoors | May 26 – Jun 26 |
| Okra | Sow outdoors | May 19 – Jun 11 |
| Peas | Sow outdoors (spring) | Mar 26 – May 11 |
| Potatoes | Plant outdoors (spring) | Mar 26 – May 26 |
| Onions | Start seeds indoors (spring) | Feb 12 – Mar 11 |
| Onions | Transplant outdoors (spring) | Apr 12 – May 11 |
| Broccoli | Start seeds indoors (spring) | Mar 8 – Apr 11 |
| Broccoli | Transplant outdoors (spring) | Apr 12 – May 11 |
| Broccoli | Start seeds indoors (fall) | Jun 10 – Jun 20 |
| Broccoli | Transplant outdoors (fall) | Jul 10 – Jul 21 |
| Cabbage | Start seeds indoors (spring) | Feb 26 – Mar 26 |
| Cabbage | Transplant outdoors (spring) | Mar 26 – Apr 26 |
| Cabbage | Start seeds indoors (fall) | May 31 – Jun 30 |
| Cabbage | Transplant outdoors (fall) | Jun 30 – Jul 31 |
| Leaf lettuce | Sow outdoors (spring) | Mar 26 – Jun 11 |
| Leaf lettuce | Sow outdoors (fall) | Jun 30 – Aug 16 |
| Spinach | Sow outdoors (spring) | Mar 19 – May 2 |
| Spinach | Sow outdoors (fall) | Jul 17 – Aug 21 |
| Radishes | Sow outdoors (spring) | Mar 26 – May 16 |
| Radishes | Sow outdoors (fall) | Jun 30 – Aug 31 |
| Kale | Sow outdoors (spring) | Apr 12 – May 2 |
| Kale | Sow outdoors (fall) | Jun 23 – Jul 31 |
| Carrots | Sow outdoors (spring) | Apr 26 – Jun 11 |
| Carrots | Sow outdoors (fall) | May 31 – Jul 16 |
| Garlic | Plant outdoors (fall) | Sep 30 – Oct 31 |
Where these dates come from
ZIP code 98844 is matched to the NOAA station Tonasket 4 Nne, WA, 17.8 km away, at 960 ft elevation (159 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Tonasket 4 Nne, WA (used) | 960 ft | Apr 26 | Oct 10 |
| Tonasket 11Ne, WA | 3,434 ft | May 6 | Oct 6 |
| Omak Ap, WA | 1,296 ft | Apr 30 | Oct 7 |
| Republic, WA | 2,555 ft | May 30 | Sep 10 |
Frost dates near Oroville
- Loomis, WA 98827 · last Apr 26, first Oct 10
- Tonasket, WA 98855 · last Apr 30, first Oct 7
- Wauconda, WA 98859 · last May 6, first Oct 6
- Conconully, WA 98819 · last May 9, first Sep 29
- Riverside, WA 98849 · last Apr 30, first Oct 7
- Curlew, WA 99118 · last May 6, first Oct 6
- Omak, WA 98841 · last Apr 30, first Oct 7
- Republic, WA 99166 · last May 30, first Sep 10
Frequently asked questions
- When is the last frost in Oroville, WA?
- For ZIP code 98844, the average last spring frost (32°F) is April 26, based on NOAA 1991-2020 climate normals for the Tonasket 4 Nne, WA weather station. There is a 1-in-10 chance of a frost after May 11.
- When is the first frost in Oroville, WA?
- The average first fall frost (32°F) is October 10. There is a 1-in-10 chance of frost by September 28, so tender plants are at risk from that point on.
- How long is the growing season in 98844?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 168 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.