Frost dates for 99169Ritzville, WA
The average last spring frost in Ritzville is May 7 and the average first fall frost is October 10, giving a typical growing season of about 153 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 7
- Average first fall frost
- Oct 10
- Growing season
- 153 days
Safer after May 27 (1-in-10 risk)
Possible by Sep 27 (1-in-10 risk)
Last frost typically in 185 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) | May 8 · May 28 · Jun 16 | Sep 10 · Sep 28 · Oct 12 | 123 days | 100% |
| Frost / freeze (32°F) | Apr 25 · May 7 · May 27 | Sep 27 · Oct 10 · Oct 25 | 153 days | 100% |
| Hard freeze (28°F) | Apr 2 · Apr 25 · May 10 | Oct 4 · Oct 21 · Nov 6 | 179 days | 100% |
Planting calendar for Ritzville
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 6 – Jun 12 |
| Tomatoes | Transplant outdoors | May 23 – Jun 20 |
| Peppers | Start seeds indoors | Apr 6 – May 7 |
| Peppers | Transplant outdoors | Jun 6 – Jul 7 |
| Eggplant | Start seeds indoors | Apr 23 – May 22 |
| Eggplant | Transplant outdoors | Jun 6 – Jul 7 |
| Cucumbers | Sow outdoors | Jun 6 – Jun 30 |
| Summer squash | Sow outdoors | May 23 – Jul 7 |
| Winter squash & pumpkins | Sow outdoors | Jun 6 – Jul 7 |
| Snap beans | Sow outdoors | May 23 – Jul 23 |
| Sweet corn | Sow outdoors | May 23 – Jun 20 |
| Watermelon & cantaloupe | Sow outdoors | Jun 6 – Jul 7 |
| Okra | Sow outdoors | May 30 – Jun 22 |
| Peas | Sow outdoors (spring) | Apr 6 – May 22 |
| Potatoes | Plant outdoors (spring) | Apr 6 – Jun 6 |
| Onions | Start seeds indoors (spring) | Feb 23 – Mar 22 |
| Onions | Transplant outdoors (spring) | Apr 23 – May 22 |
| Broccoli | Start seeds indoors (spring) | Mar 19 – Apr 22 |
| Broccoli | Transplant outdoors (spring) | Apr 23 – May 22 |
| Broccoli | Start seeds indoors (fall) | Jun 10 – Jun 20 |
| Broccoli | Transplant outdoors (fall) | Jul 10 – Jul 21 |
| Cabbage | Start seeds indoors (spring) | Mar 9 – Apr 6 |
| Cabbage | Transplant outdoors (spring) | Apr 6 – May 7 |
| Cabbage | Start seeds indoors (fall) | May 31 – Jun 30 |
| Cabbage | Transplant outdoors (fall) | Jun 30 – Jul 31 |
| Leaf lettuce | Sow outdoors (spring) | Apr 6 – Jun 22 |
| Leaf lettuce | Sow outdoors (fall) | Jun 30 – Aug 16 |
| Spinach | Sow outdoors (spring) | Mar 30 – May 13 |
| Spinach | Sow outdoors (fall) | Jul 17 – Aug 21 |
| Radishes | Sow outdoors (spring) | Apr 6 – May 27 |
| Radishes | Sow outdoors (fall) | Jun 30 – Aug 31 |
| Kale | Sow outdoors (spring) | Apr 23 – May 13 |
| Kale | Sow outdoors (fall) | Jun 23 – Jul 31 |
| Carrots | Sow outdoors (spring) | May 7 – Jun 22 |
| Carrots | Sow outdoors (fall) | May 31 – Jul 16 |
| Garlic | Plant outdoors (fall) | Sep 30 – Oct 31 |
Where these dates come from
ZIP code 99169 is matched to the NOAA station Ritzville 1 Sse, WA, 2.4 km away, at 1,864 ft elevation (0 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Ritzville 1 Sse, WA (used) | 1,864 ft | May 7 | Oct 10 |
| Lind 3 Ne, WA | 1,630 ft | May 7 | Oct 4 |
| Odessa, WA | 1,543 ft | May 14 | Sep 26 |
| Harrington, WA | 2,159 ft | May 31 | Sep 12 |
Frost dates near Ritzville
- Lamona, WA 99144 · last May 31, first Sep 12
- Mohler, WA 99154 · last May 31, first Sep 12
- Lind, WA 99341 · last May 7, first Oct 4
- Odessa, WA 99159 · last May 14, first Sep 26
- Benge, WA 99105 · last May 13, first Sep 26
- Washtucna, WA 99371 · last May 13, first Sep 26
- Harrington, WA 99134 · last May 31, first Sep 12
- Sprague, WA 99032 · last May 31, first Sep 12
Frequently asked questions
- When is the last frost in Ritzville, WA?
- For ZIP code 99169, the average last spring frost (32°F) is May 7, based on NOAA 1991-2020 climate normals for the Ritzville 1 Sse, WA weather station. There is a 1-in-10 chance of a frost after May 27.
- When is the first frost in Ritzville, WA?
- The average first fall frost (32°F) is October 10. There is a 1-in-10 chance of frost by September 27, so tender plants are at risk from that point on.
- How long is the growing season in 99169?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 153 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.