Coulee City, WA frost dates
Last spring frostMay 2median date
First fall frostOct 12median date
Growing season163 daysfrost-free
Hardiness zone6bZone 6b
How Coulee City compares
- In 8 years out of 10, the last spring frost in Coulee City falls between April 17 and May 22, a 35-day window. The first fall frost falls between September 27 and October 29.
- The median last frost is 11 days later than the Washington median of Apr 21.
- Its 163-day growing season is longer than 26% of the 491 Washington places with a regular frost season (state median 182 days).
- The last frost is 10 days later than the zone 6b median of Apr 22. Hardiness zones measure winter cold, not season length, so use these dates rather than a zone 6b chart.
- The weather station records an average of 136 nights a year at or below 32°F.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | April 17 |
| 50% (median) | May 2 |
| 10% (safe for tender plants) | May 22 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 27 |
| 50% (median) | October 12 |
| 90% (late) | October 29 |
Frost here means 32°F (0°C). A median date means half of years have their last frost earlier and half later.
Planting calendar for Coulee City, WA
Coulee City, WA frost dates — last frost May 2, first frost Oct 12, zone 6b. whenisthelastfrost.com
Crop
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Start indoors: Feb 7 to Feb 21Transplant outside: Apr 4 to Apr 18
Start indoors: Feb 21 to Mar 7Transplant outside: May 16 to May 30
Start indoors: Feb 21 to Mar 7Transplant outside: May 16 to May 30
Start indoors: Mar 7 to Mar 21Transplant outside: May 9 to May 23
Start indoors: Mar 7 to Mar 21Transplant outside: Apr 11 to Apr 25Sow outdoors: Apr 4 to May 9Plant for fall: Aug 17 to Sep 14
Start indoors: Mar 7 to Mar 21Transplant outside: Apr 4 to Apr 18Sow outdoors: Apr 4 to Apr 18Plant for fall: Aug 3 to Aug 24
Start indoors: Mar 7 to Mar 21Transplant outside: Apr 18 to May 2Plant for fall: Jul 6 to Jul 27
Start indoors: Mar 7 to Mar 21Transplant outside: Apr 11 to Apr 25Plant for fall: Jul 6 to Jul 27
Start indoors: Mar 7 to Mar 21Transplant outside: Apr 18 to May 2Plant for fall: Jul 6 to Jul 27
Start indoors: Mar 21 to Apr 4Transplant outside: May 23 to Jun 6Sow outdoors: May 23 to Jun 6
Start indoors: Mar 21 to Apr 4Transplant outside: May 9 to May 23
Sow outdoors: Mar 21 to Apr 11Plant for fall: Jul 20 to Aug 10
Sow outdoors: Mar 21 to Apr 11Plant for fall: Aug 17 to Sep 7
Sow outdoors: Mar 28 to May 9Plant for fall: Aug 31 to Sep 21
Start indoors: Apr 4 to Apr 11Transplant outside: May 16 to May 23Sow outdoors: May 9 to May 23Plant for fall: Jul 27 to Aug 10
Start indoors: Apr 4 to Apr 11Sow outdoors: May 9 to May 23Plant for fall: Aug 3 to Aug 17
Start indoors: Apr 4 to Apr 11Sow outdoors: May 9 to May 23
Start indoors: Apr 4 to Apr 11Transplant outside: May 16 to May 30
Sow outdoors: Apr 11 to May 9Plant for fall: Jul 20 to Aug 3
Sow outdoors: Apr 11 to May 9Plant for fall: Aug 3 to Aug 17
Sow outdoors: Apr 11 to May 2
Sow outdoors: Apr 18 to May 16Plant for fall: Aug 3 to Aug 17
Sow outdoors: Apr 18 to May 9Plant for fall: Aug 17 to Sep 7
Sow outdoors: May 9 to May 30Plant for fall: Jul 27 to Aug 10
Sow outdoors: May 9 to May 23
Transplant outside: May 16 to Jun 6
Plant for fall: Sep 28 to Nov 2
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Coulee City, WA
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Feb 7 – Feb 21 | Apr 4 – Apr 18 | — | — |
| Peppers | Feb 21 – Mar 7 | May 16 – May 30 | — | — |
| Eggplant | Feb 21 – Mar 7 | May 16 – May 30 | — | — |
| Tomatoes | Mar 7 – Mar 21 | May 9 – May 23 | — | — |
| Lettuce | Mar 7 – Mar 21 | Apr 11 – Apr 25 | Apr 4 – May 9 | Aug 17 – Sep 14 |
| Kale | Mar 7 – Mar 21 | Apr 4 – Apr 18 | Apr 4 – Apr 18 | Aug 3 – Aug 24 |
| Broccoli | Mar 7 – Mar 21 | Apr 18 – May 2 | — | Jul 6 – Jul 27 |
| Cabbage | Mar 7 – Mar 21 | Apr 11 – Apr 25 | — | Jul 6 – Jul 27 |
| Cauliflower | Mar 7 – Mar 21 | Apr 18 – May 2 | — | Jul 6 – Jul 27 |
| Okra | Mar 21 – Apr 4 | May 23 – Jun 6 | May 23 – Jun 6 | — |
| Basil | Mar 21 – Apr 4 | May 9 – May 23 | — | — |
| Peas | — | — | Mar 21 – Apr 11 | Jul 20 – Aug 10 |
| Spinach | — | — | Mar 21 – Apr 11 | Aug 17 – Sep 7 |
| Radishes | — | — | Mar 28 – May 9 | Aug 31 – Sep 21 |
| Cucumbers | Apr 4 – Apr 11 | May 16 – May 23 | May 9 – May 23 | Jul 27 – Aug 10 |
| Zucchini & Summer Squash | Apr 4 – Apr 11 | — | May 9 – May 23 | Aug 3 – Aug 17 |
| Winter Squash & Pumpkins | Apr 4 – Apr 11 | — | May 9 – May 23 | — |
| Melons & Watermelon | Apr 4 – Apr 11 | May 16 – May 30 | — | — |
| Carrots | — | — | Apr 11 – May 9 | Jul 20 – Aug 3 |
| Beets | — | — | Apr 11 – May 9 | Aug 3 – Aug 17 |
| Potatoes | — | — | Apr 11 – May 2 | — |
| Swiss Chard | — | — | Apr 18 – May 16 | Aug 3 – Aug 17 |
| Cilantro | — | — | Apr 18 – May 9 | Aug 17 – Sep 7 |
| Green Beans | — | — | May 9 – May 30 | Jul 27 – Aug 10 |
| Sweet Corn | — | — | May 9 – May 23 | — |
| Sweet Potatoes | — | May 16 – Jun 6 | — | — |
| Garlic | — | — | — | Sep 28 – Nov 2 |
Dates come from the median frost dates and common extension-service timing. Adjust for your soil temperature, microclimate and the varieties you grow.
About these dates
Based on 1991–2020 NOAA climate normals for the Hartline, WA weather station, 16 km away (elevation 1,906 ft (581 m)).
Frost dates near Coulee City
- Hartline May 2 · Oct 12
- Wilson Creek May 2 · Oct 12
- Stratford Apr 22 · Oct 17
- Soap Lake Apr 22 · Oct 17
- Almira Jun 1 · Sep 22
- Mansfield Apr 26 · Oct 11
- Marlin Apr 27 · Oct 8
- Electric City Apr 22 · Oct 21
- Ephrata Apr 22 · Oct 17
- Grand Coulee Apr 22 · Oct 21
Frequently asked questions
When is the last frost in Coulee City, WA?
The median last spring frost in Coulee City, WA is May 2. There is still about a 10% chance of frost after May 22, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Coulee City, WA?
The median first fall frost is October 12, with about a 10% chance of frost before September 27.
How long is the growing season in Coulee City, WA?
About 163 days between the median last spring frost and first fall frost.
What planting zone is Coulee City, WA?
Coulee City, WA is in USDA hardiness zone 6b.