Frost dates for 99134Harrington, WA
The average last spring frost in Harrington is May 31 and the average first fall frost is September 12, giving a typical growing season of about 101 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 31
- Average first fall frost
- Sep 12
- Growing season
- 101 days
Safer after Jun 28 (1-in-10 risk)
Possible by Aug 23 (1-in-10 risk)
Last frost typically in 209 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) | — | — | 62 days | 100% |
| Frost / freeze (32°F) | May 10 · May 31 · Jun 28 | Aug 23 · Sep 12 · Oct 2 | 101 days | 100% |
| Hard freeze (28°F) | Apr 24 · May 9 · May 31 | Sep 10 · Oct 1 · Oct 16 | 142 days | 100% |
Planting calendar for Harrington
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 30 – Jul 6 |
| Tomatoes | Transplant outdoors | Jun 16 – May 23 |
| Peppers | Start seeds indoors | Apr 30 – May 31 |
| Peppers | Transplant outdoors | Jun 30 – Jul 31 |
| Eggplant | Start seeds indoors | May 17 – Jun 15 |
| Eggplant | Transplant outdoors | Jun 30 – Jul 31 |
| Cucumbers | Sow outdoors | Jun 30 – Jun 2 |
| Summer squash | Sow outdoors | Jun 16 – Jul 31 |
| Winter squash & pumpkins | Sow outdoors | Jun 30 – Jul 31 |
| Snap beans | Sow outdoors | Jun 16 – Jun 25 |
| Sweet corn | Sow outdoors | Jun 16 – May 23 |
| Watermelon & cantaloupe | Sow outdoors | Jun 30 – Jul 31 |
| Okra | Sow outdoors | Jun 23 – Jul 16 |
| Peas | Sow outdoors (spring) | Apr 30 – Jun 15 |
| Potatoes | Plant outdoors (spring) | Apr 30 – Jun 30 |
| Onions | Start seeds indoors (spring) | Mar 19 – Apr 15 |
| Onions | Transplant outdoors (spring) | May 17 – Jun 15 |
| Broccoli | Start seeds indoors (spring) | Apr 12 – May 16 |
| Broccoli | Transplant outdoors (spring) | May 17 – Jun 15 |
| Broccoli | Start seeds indoors (fall) | May 13 – May 23 |
| Broccoli | Transplant outdoors (fall) | Jun 12 – Jun 23 |
| Cabbage | Start seeds indoors (spring) | Apr 2 – Apr 30 |
| Cabbage | Transplant outdoors (spring) | Apr 30 – May 31 |
| Cabbage | Start seeds indoors (fall) | May 3 – Jun 2 |
| Cabbage | Transplant outdoors (fall) | Jun 2 – Jul 3 |
| Leaf lettuce | Sow outdoors (spring) | Apr 30 – Jul 16 |
| Leaf lettuce | Sow outdoors (fall) | Jun 2 – Jul 19 |
| Spinach | Sow outdoors (spring) | Apr 23 – Jun 6 |
| Spinach | Sow outdoors (fall) | Jun 19 – Jul 24 |
| Radishes | Sow outdoors (spring) | Apr 30 – Jun 20 |
| Radishes | Sow outdoors (fall) | Jun 2 – Aug 3 |
| Kale | Sow outdoors (spring) | May 17 – Jun 6 |
| Kale | Sow outdoors (fall) | May 26 – Jul 3 |
| Carrots | Sow outdoors (spring) | May 31 – Jul 16 |
| Carrots | Sow outdoors (fall) | May 3 – Jun 18 |
| Garlic | Plant outdoors (fall) | Sep 2 – Oct 3 |
Where these dates come from
ZIP code 99134 is matched to the NOAA station Harrington, WA, 3.6 km away, at 2,159 ft elevation (36 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Harrington, WA (used) | 2,159 ft | May 31 | Sep 12 |
| Davenport, WA | 2,369 ft | Jun 6 | Sep 11 |
| Odessa, WA | 1,543 ft | May 14 | Sep 26 |
| Ritzville 1 Sse, WA | 1,864 ft | May 7 | Oct 10 |
Frost dates near Harrington
- Mohler, WA 99154 · last May 31, first Sep 12
- Lamona, WA 99144 · last May 31, first Sep 12
- Sprague, WA 99032 · last May 31, first Sep 12
- Davenport, WA 99122 · last Jun 6, first Sep 11
- Edwall, WA 99008 · last Jun 6, first Sep 11
- Odessa, WA 99159 · last May 14, first Sep 26
- Ritzville, WA 99169 · last May 7, first Oct 10
- Reardan, WA 99029 · last May 10, first Sep 26
Frequently asked questions
- When is the last frost in Harrington, WA?
- For ZIP code 99134, the average last spring frost (32°F) is May 31, based on NOAA 1991-2020 climate normals for the Harrington, WA weather station. There is a 1-in-10 chance of a frost after June 28.
- When is the first frost in Harrington, WA?
- The average first fall frost (32°F) is September 12. There is a 1-in-10 chance of frost by August 23, so tender plants are at risk from that point on.
- How long is the growing season in 99134?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 101 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.