Hermiston, OR frost dates
Last spring frostApr 27median date
First fall frostOct 7median date
Growing season163 daysfrost-free
Hardiness zone7bZone 7b
How Hermiston compares
- In 8 years out of 10, the last spring frost in Hermiston falls between April 11 and May 11, a 30-day window. The first fall frost falls between September 25 and October 21.
- The median last frost is 11 days later than the Oregon median of Apr 16.
- Its 163-day growing season is longer than 31% of the 345 Oregon places with a regular frost season (state median 193 days).
- The last frost is 22 days later than the zone 7b median of Apr 5. Hardiness zones measure winter cold, not season length, so use these dates rather than a zone 7b chart.
- The weather station records an average of 122 nights a year at or below 32°F.
- Compared with Kennewick, WA, 38 km away, the last frost here is 30 days later than there and the growing season is 53 days shorter.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | April 11 |
| 50% (median) | April 27 |
| 10% (safe for tender plants) | May 11 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 25 |
| 50% (median) | October 7 |
| 90% (late) | October 21 |
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 Hermiston, OR
Hermiston, OR frost dates — last frost Apr 27, first frost Oct 7, zone 7b. whenisthelastfrost.com
Crop
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Start indoors: Feb 2 to Feb 16Transplant outside: Mar 30 to Apr 13
Start indoors: Feb 16 to Mar 2Transplant outside: May 11 to May 25
Start indoors: Feb 16 to Mar 2Transplant outside: May 11 to May 25
Start indoors: Mar 2 to Mar 16Transplant outside: May 4 to May 18
Start indoors: Mar 2 to Mar 16Transplant outside: Apr 6 to Apr 20Sow outdoors: Mar 30 to May 4Plant for fall: Aug 12 to Sep 9
Start indoors: Mar 2 to Mar 16Transplant outside: Mar 30 to Apr 13Sow outdoors: Mar 30 to Apr 13Plant for fall: Jul 29 to Aug 19
Start indoors: Mar 2 to Mar 16Transplant outside: Apr 13 to Apr 27Plant for fall: Jul 1 to Jul 22
Start indoors: Mar 2 to Mar 16Transplant outside: Apr 6 to Apr 20Plant for fall: Jul 1 to Jul 22
Start indoors: Mar 2 to Mar 16Transplant outside: Apr 13 to Apr 27Plant for fall: Jul 1 to Jul 22
Start indoors: Mar 16 to Mar 30Transplant outside: May 18 to Jun 1Sow outdoors: May 18 to Jun 1
Start indoors: Mar 16 to Mar 30Transplant outside: May 4 to May 18
Sow outdoors: Mar 16 to Apr 6Plant for fall: Jul 15 to Aug 5
Sow outdoors: Mar 16 to Apr 6Plant for fall: Aug 12 to Sep 2
Sow outdoors: Mar 23 to May 4Plant for fall: Aug 26 to Sep 16
Start indoors: Mar 30 to Apr 6Transplant outside: May 11 to May 18Sow outdoors: May 4 to May 18Plant for fall: Jul 22 to Aug 5
Start indoors: Mar 30 to Apr 6Sow outdoors: May 4 to May 18Plant for fall: Jul 29 to Aug 12
Start indoors: Mar 30 to Apr 6Sow outdoors: May 4 to May 18
Start indoors: Mar 30 to Apr 6Transplant outside: May 11 to May 25
Sow outdoors: Apr 6 to May 4Plant for fall: Jul 15 to Jul 29
Sow outdoors: Apr 6 to May 4Plant for fall: Jul 29 to Aug 12
Sow outdoors: Apr 6 to Apr 27
Sow outdoors: Apr 13 to May 11Plant for fall: Jul 29 to Aug 12
Sow outdoors: Apr 13 to May 4Plant for fall: Aug 12 to Sep 2
Sow outdoors: May 4 to May 25Plant for fall: Jul 22 to Aug 5
Sow outdoors: May 4 to May 18
Transplant outside: May 11 to Jun 1
Plant for fall: Sep 23 to Oct 28
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Hermiston, OR
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Feb 2 – Feb 16 | Mar 30 – Apr 13 | — | — |
| Peppers | Feb 16 – Mar 2 | May 11 – May 25 | — | — |
| Eggplant | Feb 16 – Mar 2 | May 11 – May 25 | — | — |
| Tomatoes | Mar 2 – Mar 16 | May 4 – May 18 | — | — |
| Lettuce | Mar 2 – Mar 16 | Apr 6 – Apr 20 | Mar 30 – May 4 | Aug 12 – Sep 9 |
| Kale | Mar 2 – Mar 16 | Mar 30 – Apr 13 | Mar 30 – Apr 13 | Jul 29 – Aug 19 |
| Broccoli | Mar 2 – Mar 16 | Apr 13 – Apr 27 | — | Jul 1 – Jul 22 |
| Cabbage | Mar 2 – Mar 16 | Apr 6 – Apr 20 | — | Jul 1 – Jul 22 |
| Cauliflower | Mar 2 – Mar 16 | Apr 13 – Apr 27 | — | Jul 1 – Jul 22 |
| Okra | Mar 16 – Mar 30 | May 18 – Jun 1 | May 18 – Jun 1 | — |
| Basil | Mar 16 – Mar 30 | May 4 – May 18 | — | — |
| Peas | — | — | Mar 16 – Apr 6 | Jul 15 – Aug 5 |
| Spinach | — | — | Mar 16 – Apr 6 | Aug 12 – Sep 2 |
| Radishes | — | — | Mar 23 – May 4 | Aug 26 – Sep 16 |
| Cucumbers | Mar 30 – Apr 6 | May 11 – May 18 | May 4 – May 18 | Jul 22 – Aug 5 |
| Zucchini & Summer Squash | Mar 30 – Apr 6 | — | May 4 – May 18 | Jul 29 – Aug 12 |
| Winter Squash & Pumpkins | Mar 30 – Apr 6 | — | May 4 – May 18 | — |
| Melons & Watermelon | Mar 30 – Apr 6 | May 11 – May 25 | — | — |
| Carrots | — | — | Apr 6 – May 4 | Jul 15 – Jul 29 |
| Beets | — | — | Apr 6 – May 4 | Jul 29 – Aug 12 |
| Potatoes | — | — | Apr 6 – Apr 27 | — |
| Swiss Chard | — | — | Apr 13 – May 11 | Jul 29 – Aug 12 |
| Cilantro | — | — | Apr 13 – May 4 | Aug 12 – Sep 2 |
| Green Beans | — | — | May 4 – May 25 | Jul 22 – Aug 5 |
| Sweet Corn | — | — | May 4 – May 18 | — |
| Sweet Potatoes | — | May 11 – Jun 1 | — | — |
| Garlic | — | — | — | Sep 23 – Oct 28 |
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 Hermiston 2 Nw, OR weather station, 3 km away (elevation 459 ft (140 m)).
Frost dates near Hermiston
- Umatilla Apr 27 · Oct 7
- Stanfield Apr 26 · Oct 10
- Echo Apr 26 · Oct 10
- Irrigon Apr 14 · Oct 21
- Boardman Apr 14 · Oct 21
- Helix May 12 · Sep 27
- Pendleton Apr 22 · Oct 9
- Ione Apr 26 · Oct 19
- Adams May 12 · Sep 27
- Pilot Rock May 7 · Oct 4
Frequently asked questions
When is the last frost in Hermiston, OR?
The median last spring frost in Hermiston, OR is April 27. There is still about a 10% chance of frost after May 11, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Hermiston, OR?
The median first fall frost is October 7, with about a 10% chance of frost before September 25.
How long is the growing season in Hermiston, OR?
About 163 days between the median last spring frost and first fall frost.
What planting zone is Hermiston, OR?
Hermiston, OR is in USDA hardiness zone 7b.