In Oregon, the last spring frost usually comes between March 20 and June 4, and the first fall frost between September 14 and November 22, depending on where you live. Most of Oregon is in USDA hardiness zones 6a to 9a. In the highest mountain areas, frost is possible in any month.
Find the frost dates for your ZIP code
Frost dates from NOAA 1991–2020 U.S. Climate Normals, nearest weather station. Zones derived from the 2023 USDA Plant Hardiness Zone Map data (PRISM Climate Group, Oregon State University). This is not the official USDA Plant Hardiness Zone Map.
Frost dates for Oregon cities
Dates come from the NOAA weather station closest to each city. The last spring frost and first fall frost are the typical dates, with a 30% chance of frost after (or before) them. The safer planting date has only a 10% chance of a later spring frost: use it for tender plants like tomatoes, peppers and basil.
| City | Zone | Last frost | Safer date | First frost |
|---|---|---|---|---|
| Portland | 9a | March 6 | March 21 | Nov. 22 |
| Salem | 8b | April 13 | April 27 | Oct. 26 |
| Eugene | 8b | April 25 | May 9 | Oct. 15 |
| Bend | 6b | June 14 | June 22 | Sep. 12 |
| Medford | 8b | April 18 | April 30 | Oct. 23 |
| Corvallis | 8b | April 27 | May 8 | Oct. 20 |
| Roseburg | 8b | April 10 | April 26 | Oct. 28 |
| Klamath Falls | 6b | June 16 | June 26 | Sep. 13 |
| Hermiston | 7b | May 3 | May 11 | Oct. 2 |
| Pendleton | 7a | April 30 | May 8 | Oct. 3 |
Frost dates vary a lot across Oregon. Among the cities above, Portland has the earliest last frost (around March 6) and Klamath Falls the latest (around June 16), about 15 weeks apart. Elevation, nearby water and local terrain all make a difference, so use the dates for the place closest to you, or look up your ZIP code.
Growing zones in Oregon
Most of Oregon is in USDA hardiness zones 6a to 9a. A typical frost-free growing season lasts about 215 days, longer in the warmest areas and shorter in the coldest.
Find planting dates for the main zones in Oregon:
- Zone 6 (about 20% of ZIP codes): Tomatoes, Peppers, Potatoes, Lettuce, Green beans, Cucumbers, Garlic, Tulips
- Zone 7 (about 12% of ZIP codes): Tomatoes, Peppers, Potatoes, Lettuce, Green beans, Cucumbers, Garlic, Tulips
- Zone 8 (about 45% of ZIP codes): Tomatoes, Peppers, Potatoes, Lettuce, Green beans, Cucumbers, Garlic, Tulips
- Zone 9 (about 23% of ZIP codes): Tomatoes, Peppers, Potatoes, Lettuce, Green beans, Cucumbers, Garlic, Tulips
See all crops in our planting guides, or build a planting calendar for your ZIP code.
How to use frost dates
- Cool-season crops such as peas, lettuce, spinach and onions can go in several weeks before your last spring frost.
- Warm-season crops such as tomatoes, peppers, squash and beans wait until after it, when the soil has warmed.
- Fall crops are timed back from your first fall frost, and garlic and tulips are planted around it.
- Frost dates are averages. Check the forecast before setting out tender plants.
Frequently asked questions
When is the last frost in Oregon?
It depends on where you live. Across most of Oregon, the last spring frost comes between March 20 and June 4. In Portland, it is around March 6.
When is the first frost in Oregon?
Across most of Oregon, the first fall frost comes between September 14 and November 22. In Portland, it is around November 22.
What planting zone is Oregon?
Most of Oregon is in USDA hardiness zones 6a to 9a. Enter your ZIP code above to find your exact zone.
When can I plant tomatoes in Oregon?
Plant tomatoes outside after your last frost, once nights stay above 50 °F. In Portland, the safer date, with only a 10% chance of a later frost, is around March 21. See when to plant tomatoes in zone 9.
Sources. Frost dates come from the nearest NOAA weather station to each city or ZIP code. Zones come from the 2023 USDA Plant Hardiness Zone Map ZIP code data. Our zone lookup is not the official USDA map.