Mattawa, WA frost dates
Last spring frostMar 24median date
First fall frostNov 4median date
Growing season225 daysfrost-free
Hardiness zone7aZone 7a
How Mattawa compares
- In 8 years out of 10, the last spring frost in Mattawa falls between March 4 and April 7, a 34-day window. The first fall frost falls between October 23 and November 18.
- The median last frost is 28 days earlier than the Washington median of Apr 21.
- Its 225-day growing season is longer than 80% of the 491 Washington places with a regular frost season (state median 182 days).
- The last frost is 23 days earlier than the zone 7a median of Apr 16. Hardiness zones measure winter cold, not season length, so use these dates rather than a zone 7a chart.
- The weather station records an average of 75 nights a year at or below 32°F.
- Compared with Richland, WA, 61 km away, the last frost here is 13 days earlier than there and the growing season is 24 days longer.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | March 4 |
| 50% (median) | March 24 |
| 10% (safe for tender plants) | April 7 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | October 23 |
| 50% (median) | November 4 |
| 90% (late) | November 18 |
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 Mattawa, WA
Mattawa, WA frost dates — last frost Mar 24, first frost Nov 4, zone 7a. whenisthelastfrost.com
Crop
JFMAMJJASOND
Start indoors: Dec 30 to Jan 13Start indoors: Dec 30 to Jan 13Transplant outside: Feb 24 to Mar 10
Start indoors: Jan 13 to Jan 27Transplant outside: Apr 7 to Apr 21
Start indoors: Jan 13 to Jan 27Transplant outside: Apr 7 to Apr 21
Start indoors: Jan 27 to Feb 10Transplant outside: Mar 31 to Apr 14
Start indoors: Jan 27 to Feb 10Transplant outside: Mar 3 to Mar 17Sow outdoors: Feb 24 to Mar 31Plant for fall: Sep 9 to Oct 7
Start indoors: Jan 27 to Feb 10Transplant outside: Feb 24 to Mar 10Sow outdoors: Feb 24 to Mar 10Plant for fall: Aug 26 to Sep 16
Start indoors: Jan 27 to Feb 10Transplant outside: Mar 10 to Mar 24Plant for fall: Jul 29 to Aug 19
Start indoors: Jan 27 to Feb 10Transplant outside: Mar 3 to Mar 17Plant for fall: Jul 29 to Aug 19
Start indoors: Jan 27 to Feb 10Transplant outside: Mar 10 to Mar 24Plant for fall: Jul 29 to Aug 19
Start indoors: Feb 10 to Feb 24Transplant outside: Apr 14 to Apr 28Sow outdoors: Apr 14 to Apr 28
Start indoors: Feb 10 to Feb 24Transplant outside: Mar 31 to Apr 14
Sow outdoors: Feb 10 to Mar 3Plant for fall: Aug 12 to Sep 2
Sow outdoors: Feb 10 to Mar 3Plant for fall: Sep 9 to Sep 30
Sow outdoors: Feb 17 to Mar 31Plant for fall: Sep 23 to Oct 14
Start indoors: Feb 24 to Mar 3Transplant outside: Apr 7 to Apr 14Sow outdoors: Mar 31 to Apr 14Plant for fall: Aug 19 to Sep 2
Start indoors: Feb 24 to Mar 3Sow outdoors: Mar 31 to Apr 14Plant for fall: Aug 26 to Sep 9
Start indoors: Feb 24 to Mar 3Sow outdoors: Mar 31 to Apr 14
Start indoors: Feb 24 to Mar 3Transplant outside: Apr 7 to Apr 21
Sow outdoors: Mar 3 to Mar 31Plant for fall: Aug 12 to Aug 26
Sow outdoors: Mar 3 to Mar 31Plant for fall: Aug 26 to Sep 9
Sow outdoors: Mar 3 to Mar 24
Sow outdoors: Mar 10 to Apr 7Plant for fall: Aug 26 to Sep 9
Sow outdoors: Mar 10 to Mar 31Plant for fall: Sep 9 to Sep 30
Sow outdoors: Mar 31 to Apr 21Plant for fall: Aug 19 to Sep 2
Sow outdoors: Mar 31 to Apr 14
Transplant outside: Apr 7 to Apr 28
Plant for fall: Oct 21 to Nov 25
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Mattawa, WA
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Dec 30 – Jan 13 | Feb 24 – Mar 10 | — | — |
| Peppers | Jan 13 – Jan 27 | Apr 7 – Apr 21 | — | — |
| Eggplant | Jan 13 – Jan 27 | Apr 7 – Apr 21 | — | — |
| Tomatoes | Jan 27 – Feb 10 | Mar 31 – Apr 14 | — | — |
| Lettuce | Jan 27 – Feb 10 | Mar 3 – Mar 17 | Feb 24 – Mar 31 | Sep 9 – Oct 7 |
| Kale | Jan 27 – Feb 10 | Feb 24 – Mar 10 | Feb 24 – Mar 10 | Aug 26 – Sep 16 |
| Broccoli | Jan 27 – Feb 10 | Mar 10 – Mar 24 | — | Jul 29 – Aug 19 |
| Cabbage | Jan 27 – Feb 10 | Mar 3 – Mar 17 | — | Jul 29 – Aug 19 |
| Cauliflower | Jan 27 – Feb 10 | Mar 10 – Mar 24 | — | Jul 29 – Aug 19 |
| Okra | Feb 10 – Feb 24 | Apr 14 – Apr 28 | Apr 14 – Apr 28 | — |
| Basil | Feb 10 – Feb 24 | Mar 31 – Apr 14 | — | — |
| Peas | — | — | Feb 10 – Mar 3 | Aug 12 – Sep 2 |
| Spinach | — | — | Feb 10 – Mar 3 | Sep 9 – Sep 30 |
| Radishes | — | — | Feb 17 – Mar 31 | Sep 23 – Oct 14 |
| Cucumbers | Feb 24 – Mar 3 | Apr 7 – Apr 14 | Mar 31 – Apr 14 | Aug 19 – Sep 2 |
| Zucchini & Summer Squash | Feb 24 – Mar 3 | — | Mar 31 – Apr 14 | Aug 26 – Sep 9 |
| Winter Squash & Pumpkins | Feb 24 – Mar 3 | — | Mar 31 – Apr 14 | — |
| Melons & Watermelon | Feb 24 – Mar 3 | Apr 7 – Apr 21 | — | — |
| Carrots | — | — | Mar 3 – Mar 31 | Aug 12 – Aug 26 |
| Beets | — | — | Mar 3 – Mar 31 | Aug 26 – Sep 9 |
| Potatoes | — | — | Mar 3 – Mar 24 | — |
| Swiss Chard | — | — | Mar 10 – Apr 7 | Aug 26 – Sep 9 |
| Cilantro | — | — | Mar 10 – Mar 31 | Sep 9 – Sep 30 |
| Green Beans | — | — | Mar 31 – Apr 21 | Aug 19 – Sep 2 |
| Sweet Corn | — | — | Mar 31 – Apr 14 | — |
| Sweet Potatoes | — | Apr 7 – Apr 28 | — | — |
| Garlic | — | — | — | Oct 21 – Nov 25 |
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 Priest Rapids Dam, WA weather station, 14 km away (elevation 430 ft (131 m)).
Frost dates near Mattawa
- Beverly Apr 23 · Oct 12
- Vantage Apr 23 · Oct 12
- Royal City Apr 23 · Oct 12
- George Apr 21 · Oct 16
- Outlook Apr 30 · Oct 8
- Sunnyside May 1 · Oct 6
- Moxee May 8 · Oct 4
- Zillah Apr 21 · Oct 15
- Mesa Apr 21 · Oct 22
- Quincy Apr 21 · Oct 16
Frequently asked questions
When is the last frost in Mattawa, WA?
The median last spring frost in Mattawa, WA is March 24. There is still about a 10% chance of frost after April 7, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Mattawa, WA?
The median first fall frost is November 4, with about a 10% chance of frost before October 23.
How long is the growing season in Mattawa, WA?
About 225 days between the median last spring frost and first fall frost.
What planting zone is Mattawa, WA?
Mattawa, WA is in USDA hardiness zone 7a.