Hamilton, WA frost dates
Last spring frostMar 28median date
First fall frostNov 14median date
Growing season231 daysfrost-free
Hardiness zone8bZone 8b
How Hamilton compares
- In 8 years out of 10, the last spring frost in Hamilton falls between March 7 and April 19, a 43-day window. The first fall frost falls between October 23 and December 4.
- The median last frost is 24 days earlier than the Washington median of Apr 21.
- Its 231-day growing season is longer than 85% of the 491 Washington places with a regular frost season (state median 182 days).
- The last frost is 12 days later than the zone 8b median of Mar 16. Hardiness zones measure winter cold, not season length, so use these dates rather than a zone 8b chart.
- The weather station records an average of 47 nights a year at or below 32°F.
- Compared with Bellingham, WA, 43 km away, the last frost here is 4 days earlier than there and the growing season is 16 days longer.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | March 7 |
| 50% (median) | March 28 |
| 10% (safe for tender plants) | April 19 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | October 23 |
| 50% (median) | November 14 |
| 90% (late) | December 4 |
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 Hamilton, WA
Hamilton, WA frost dates — last frost Mar 28, first frost Nov 14, zone 8b. whenisthelastfrost.com
Crop
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Start indoors: Jan 3 to Jan 17Transplant outside: Feb 28 to Mar 14
Start indoors: Jan 17 to Jan 31Transplant outside: Apr 11 to Apr 25
Start indoors: Jan 17 to Jan 31Transplant outside: Apr 11 to Apr 25
Start indoors: Jan 31 to Feb 14Transplant outside: Apr 4 to Apr 18
Start indoors: Jan 31 to Feb 14Transplant outside: Mar 7 to Mar 21Sow outdoors: Feb 28 to Apr 4Plant for fall: Sep 19 to Oct 17
Start indoors: Jan 31 to Feb 14Transplant outside: Feb 28 to Mar 14Sow outdoors: Feb 28 to Mar 14Plant for fall: Sep 5 to Sep 26
Start indoors: Jan 31 to Feb 14Transplant outside: Mar 14 to Mar 28Plant for fall: Aug 8 to Aug 29
Start indoors: Jan 31 to Feb 14Transplant outside: Mar 7 to Mar 21Plant for fall: Aug 8 to Aug 29
Start indoors: Jan 31 to Feb 14Transplant outside: Mar 14 to Mar 28Plant for fall: Aug 8 to Aug 29
Start indoors: Feb 14 to Feb 28Transplant outside: Apr 18 to May 2Sow outdoors: Apr 18 to May 2
Start indoors: Feb 14 to Feb 28Transplant outside: Apr 4 to Apr 18
Sow outdoors: Feb 14 to Mar 7Plant for fall: Aug 22 to Sep 12
Sow outdoors: Feb 14 to Mar 7Plant for fall: Sep 19 to Oct 10
Sow outdoors: Feb 21 to Apr 4Plant for fall: Oct 3 to Oct 24
Start indoors: Feb 28 to Mar 7Transplant outside: Apr 11 to Apr 18Sow outdoors: Apr 4 to Apr 18Plant for fall: Aug 29 to Sep 12
Start indoors: Feb 28 to Mar 7Sow outdoors: Apr 4 to Apr 18Plant for fall: Sep 5 to Sep 19
Start indoors: Feb 28 to Mar 7Sow outdoors: Apr 4 to Apr 18
Start indoors: Feb 28 to Mar 7Transplant outside: Apr 11 to Apr 25
Sow outdoors: Mar 7 to Apr 4Plant for fall: Aug 22 to Sep 5
Sow outdoors: Mar 7 to Apr 4Plant for fall: Sep 5 to Sep 19
Sow outdoors: Mar 7 to Mar 28
Sow outdoors: Mar 14 to Apr 11Plant for fall: Sep 5 to Sep 19
Sow outdoors: Mar 14 to Apr 4Plant for fall: Sep 19 to Oct 10
Sow outdoors: Apr 4 to Apr 25Plant for fall: Aug 29 to Sep 12
Sow outdoors: Apr 4 to Apr 18
Transplant outside: Apr 11 to May 2
Plant for fall: Oct 31 to Dec 5
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Hamilton, WA
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Jan 3 – Jan 17 | Feb 28 – Mar 14 | — | — |
| Peppers | Jan 17 – Jan 31 | Apr 11 – Apr 25 | — | — |
| Eggplant | Jan 17 – Jan 31 | Apr 11 – Apr 25 | — | — |
| Tomatoes | Jan 31 – Feb 14 | Apr 4 – Apr 18 | — | — |
| Lettuce | Jan 31 – Feb 14 | Mar 7 – Mar 21 | Feb 28 – Apr 4 | Sep 19 – Oct 17 |
| Kale | Jan 31 – Feb 14 | Feb 28 – Mar 14 | Feb 28 – Mar 14 | Sep 5 – Sep 26 |
| Broccoli | Jan 31 – Feb 14 | Mar 14 – Mar 28 | — | Aug 8 – Aug 29 |
| Cabbage | Jan 31 – Feb 14 | Mar 7 – Mar 21 | — | Aug 8 – Aug 29 |
| Cauliflower | Jan 31 – Feb 14 | Mar 14 – Mar 28 | — | Aug 8 – Aug 29 |
| Okra | Feb 14 – Feb 28 | Apr 18 – May 2 | Apr 18 – May 2 | — |
| Basil | Feb 14 – Feb 28 | Apr 4 – Apr 18 | — | — |
| Peas | — | — | Feb 14 – Mar 7 | Aug 22 – Sep 12 |
| Spinach | — | — | Feb 14 – Mar 7 | Sep 19 – Oct 10 |
| Radishes | — | — | Feb 21 – Apr 4 | Oct 3 – Oct 24 |
| Cucumbers | Feb 28 – Mar 7 | Apr 11 – Apr 18 | Apr 4 – Apr 18 | Aug 29 – Sep 12 |
| Zucchini & Summer Squash | Feb 28 – Mar 7 | — | Apr 4 – Apr 18 | Sep 5 – Sep 19 |
| Winter Squash & Pumpkins | Feb 28 – Mar 7 | — | Apr 4 – Apr 18 | — |
| Melons & Watermelon | Feb 28 – Mar 7 | Apr 11 – Apr 25 | — | — |
| Carrots | — | — | Mar 7 – Apr 4 | Aug 22 – Sep 5 |
| Beets | — | — | Mar 7 – Apr 4 | Sep 5 – Sep 19 |
| Potatoes | — | — | Mar 7 – Mar 28 | — |
| Swiss Chard | — | — | Mar 14 – Apr 11 | Sep 5 – Sep 19 |
| Cilantro | — | — | Mar 14 – Apr 4 | Sep 19 – Oct 10 |
| Green Beans | — | — | Apr 4 – Apr 25 | Aug 29 – Sep 12 |
| Sweet Corn | — | — | Apr 4 – Apr 18 | — |
| Sweet Potatoes | — | Apr 11 – May 2 | — | — |
| Garlic | — | — | — | Oct 31 – Dec 5 |
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 Concrete Ppl Fish Stn, WA weather station, 18 km away (elevation 194 ft (59 m)).
Frost dates near Hamilton
- Lyman Mar 27 · Nov 6
- Sedro Woolley Mar 27 · Nov 6
- Clearlake Mar 27 · Nov 6
- Mount Vernon Mar 27 · Nov 6
- Acme Mar 27 · Nov 6
- Concrete Mar 28 · Nov 14
- Burlington Mar 24 · Nov 3
- Bow Mar 24 · Nov 3
- Deming Apr 18 · Oct 18
- Rockport Apr 16 · Oct 25
Frequently asked questions
When is the last frost in Hamilton, WA?
The median last spring frost in Hamilton, WA is March 28. There is still about a 10% chance of frost after April 19, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Hamilton, WA?
The median first fall frost is November 14, with about a 10% chance of frost before October 23.
How long is the growing season in Hamilton, WA?
About 231 days between the median last spring frost and first fall frost.
What planting zone is Hamilton, WA?
Hamilton, WA is in USDA hardiness zone 8b.