Frost dates for 98926Ellensburg, WA
The average last spring frost in Ellensburg is May 8 and the average first fall frost is October 2, giving a typical growing season of about 146 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 8
- Average first fall frost
- Oct 2
- Growing season
- 146 days
Safer after May 25 (1-in-10 risk)
Possible by Sep 20 (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) | May 8 · May 23 · Jun 16 | Sep 8 · Sep 21 · Oct 2 | 118 days | 100% |
| Frost / freeze (32°F) | Apr 25 · May 8 · May 25 | Sep 20 · Oct 2 · Oct 14 | 146 days | 100% |
| Hard freeze (28°F) | Apr 9 · Apr 23 · May 6 | Oct 1 · Oct 14 · Oct 28 | 173 days | 100% |
Planting calendar for Ellensburg
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 7 – Jun 13 |
| Tomatoes | Transplant outdoors | May 24 – Jun 12 |
| Peppers | Start seeds indoors | Apr 7 – May 8 |
| Peppers | Transplant outdoors | Jun 7 – Jul 8 |
| Eggplant | Start seeds indoors | Apr 24 – May 23 |
| Eggplant | Transplant outdoors | Jun 7 – Jul 8 |
| Cucumbers | Sow outdoors | Jun 7 – Jun 22 |
| Summer squash | Sow outdoors | May 24 – Jul 8 |
| Winter squash & pumpkins | Sow outdoors | Jun 7 – Jul 8 |
| Snap beans | Sow outdoors | May 24 – Jul 15 |
| Sweet corn | Sow outdoors | May 24 – Jun 12 |
| Watermelon & cantaloupe | Sow outdoors | Jun 7 – Jul 8 |
| Okra | Sow outdoors | May 31 – Jun 23 |
| Peas | Sow outdoors (spring) | Apr 7 – May 23 |
| Potatoes | Plant outdoors (spring) | Apr 7 – Jun 7 |
| Onions | Start seeds indoors (spring) | Feb 24 – Mar 23 |
| Onions | Transplant outdoors (spring) | Apr 24 – May 23 |
| Broccoli | Start seeds indoors (spring) | Mar 20 – Apr 23 |
| Broccoli | Transplant outdoors (spring) | Apr 24 – May 23 |
| Broccoli | Start seeds indoors (fall) | Jun 2 – Jun 12 |
| Broccoli | Transplant outdoors (fall) | Jul 2 – Jul 13 |
| Cabbage | Start seeds indoors (spring) | Mar 10 – Apr 7 |
| Cabbage | Transplant outdoors (spring) | Apr 7 – May 8 |
| Cabbage | Start seeds indoors (fall) | May 23 – Jun 22 |
| Cabbage | Transplant outdoors (fall) | Jun 22 – Jul 23 |
| Leaf lettuce | Sow outdoors (spring) | Apr 7 – Jun 23 |
| Leaf lettuce | Sow outdoors (fall) | Jun 22 – Aug 8 |
| Spinach | Sow outdoors (spring) | Mar 31 – May 14 |
| Spinach | Sow outdoors (fall) | Jul 9 – Aug 13 |
| Radishes | Sow outdoors (spring) | Apr 7 – May 28 |
| Radishes | Sow outdoors (fall) | Jun 22 – Aug 23 |
| Kale | Sow outdoors (spring) | Apr 24 – May 14 |
| Kale | Sow outdoors (fall) | Jun 15 – Jul 23 |
| Carrots | Sow outdoors (spring) | May 8 – Jun 23 |
| Carrots | Sow outdoors (fall) | May 23 – Jul 8 |
| Garlic | Plant outdoors (fall) | Sep 22 – Oct 23 |
Where these dates come from
ZIP code 98926 is matched to the NOAA station Ellensburg, WA, 3.8 km away, at 1,480 ft elevation (128 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Ellensburg, WA (used) | 1,480 ft | May 8 | Oct 2 |
| Ellensburg Bowers Fld, WA | 1,766 ft | Apr 28 | Oct 7 |
| Selah 2 Ne, WA | 1,120 ft | May 5 | Oct 4 |
| Cle Elum, WA | 1,900 ft | May 13 | Sep 25 |
Frost dates near Ellensburg
- Kittitas, WA 98934 · last Apr 28, first Oct 7
- Thorp, WA 98946 · last Apr 28, first Oct 7
- Selah, WA 98942 · last May 5, first Oct 4
- Tieton, WA 98947 · last Apr 28, first Oct 7
- South Cle Elum, WA 98943 · last May 13, first Sep 25
- Cowiche, WA 98923 · last Apr 28, first Oct 7
- Cle Elum, WA 98922 · last May 13, first Sep 25
- Yakima, WA 98907 · last May 5, first Oct 4
Frequently asked questions
- When is the last frost in Ellensburg, WA?
- For ZIP code 98926, the average last spring frost (32°F) is May 8, based on NOAA 1991-2020 climate normals for the Ellensburg, WA weather station. There is a 1-in-10 chance of a frost after May 25.
- When is the first frost in Ellensburg, WA?
- The average first fall frost (32°F) is October 2. There is a 1-in-10 chance of frost by September 20, so tender plants are at risk from that point on.
- How long is the growing season in 98926?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 146 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.