Frost dates for 97233Portland, OR
The average last spring frost in Portland is March 13 and the average first fall frost is November 22, giving a typical growing season of about 251 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Mar 13
- Average first fall frost
- Nov 22
- Growing season
- 251 days
Safer after Apr 5 (1-in-10 risk)
Possible by Nov 3 (1-in-10 risk)
First frost typically in 20 days
Frost risk by date
NOAA reports frost dates as probabilities. The middle date is the average (a 50% chance). For spring, the 10% date is a safer planting date: frost after it happens in about 1 year in 10. Light frost (36°F) can damage tender plants; a hard freeze (28°F) kills most annuals.
| Temperature | Last spring: 90% / 50% / 10% chance | First fall: 10% / 50% / 90% chance | Growing season (50%) | Years with at least one |
|---|---|---|---|---|
| Light frost (36°F) | Mar 22 · Apr 10 · May 1 | Oct 20 · Nov 5 · Nov 22 | 206 days | 100% |
| Frost / freeze (32°F) | Feb 20 · Mar 13 · Apr 5 | Nov 3 · Nov 22 · Dec 14 | 251 days | 100% |
| Hard freeze (28°F) | Dec 27 · Feb 12 · Mar 7 | Nov 15 · Dec 10 · Jan 22 | 307 days | 94% |
Planting calendar for Portland
Planting windows from the University of Maryland Extension calendar, shifted to your average frost dates. Use them as a starting point and adjust for seed packet instructions and local conditions.
| Crop | Task | Window |
|---|---|---|
| Tomatoes | Start seeds indoors | Feb 10 – Apr 18 |
| Tomatoes | Transplant outdoors | Mar 29 – Aug 2 |
| Peppers | Start seeds indoors | Feb 10 – Mar 13 |
| Peppers | Transplant outdoors | Apr 12 – May 13 |
| Eggplant | Start seeds indoors | Feb 27 – Mar 28 |
| Eggplant | Transplant outdoors | Apr 12 – May 13 |
| Cucumbers | Sow outdoors | Apr 12 – Aug 12 |
| Summer squash | Sow outdoors | Mar 29 – May 13 |
| Winter squash & pumpkins | Sow outdoors | Apr 12 – May 13 |
| Snap beans | Sow outdoors | Mar 29 – Sep 4 |
| Sweet corn | Sow outdoors | Mar 29 – Aug 2 |
| Watermelon & cantaloupe | Sow outdoors | Apr 12 – May 13 |
| Okra | Sow outdoors | Apr 5 – Apr 28 |
| Peas | Sow outdoors (spring) | Feb 10 – Mar 28 |
| Potatoes | Plant outdoors (spring) | Feb 10 – Apr 12 |
| Onions | Start seeds indoors (spring) | Dec 30 – Jan 26 |
| Onions | Transplant outdoors (spring) | Feb 27 – Mar 28 |
| Broccoli | Start seeds indoors (spring) | Jan 23 – Feb 26 |
| Broccoli | Transplant outdoors (spring) | Feb 27 – Mar 28 |
| Broccoli | Start seeds indoors (fall) | Jul 23 – Aug 2 |
| Broccoli | Transplant outdoors (fall) | Aug 22 – Sep 2 |
| Cabbage | Start seeds indoors (spring) | Jan 13 – Feb 10 |
| Cabbage | Transplant outdoors (spring) | Feb 10 – Mar 13 |
| Cabbage | Start seeds indoors (fall) | Jul 13 – Aug 12 |
| Cabbage | Transplant outdoors (fall) | Aug 12 – Sep 12 |
| Leaf lettuce | Sow outdoors (spring) | Feb 10 – Apr 28 |
| Leaf lettuce | Sow outdoors (fall) | Aug 12 – Sep 28 |
| Spinach | Sow outdoors (spring) | Feb 3 – Mar 19 |
| Spinach | Sow outdoors (fall) | Aug 29 – Oct 3 |
| Radishes | Sow outdoors (spring) | Feb 10 – Apr 2 |
| Radishes | Sow outdoors (fall) | Aug 12 – Oct 13 |
| Kale | Sow outdoors (spring) | Feb 27 – Mar 19 |
| Kale | Sow outdoors (fall) | Aug 5 – Sep 12 |
| Carrots | Sow outdoors (spring) | Mar 13 – Apr 28 |
| Carrots | Sow outdoors (fall) | Jul 13 – Aug 28 |
| Garlic | Plant outdoors (fall) | Nov 12 – Dec 13 |
Where these dates come from
ZIP code 97233 is matched to the NOAA station Portland Wfo, OR, 6 km away, at 21 ft elevation (222 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Portland Wfo, OR (used) | 21 ft | Mar 13 | Nov 22 |
| Portland Troutdale Ap, OR | 29 ft | Mar 16 | Nov 20 |
| Troutdale, OR | 33 ft | Mar 26 | Nov 17 |
| Portland Intl Ap, OR | 19 ft | Mar 13 | Nov 19 |
Frost dates near Portland
- Portland, OR 97236 · last Feb 25, first Dec 1
- Fairview, OR 97024 · last Mar 16, first Nov 20
- Gresham, OR 97030 · last Mar 16, first Nov 20
- Happy Valley, OR 97086 · last Mar 18, first Nov 18
- Troutdale, OR 97060 · last Mar 26, first Nov 17
- Vancouver, WA 98683 · last Apr 26, first Oct 18
- Clackamas, OR 97015 · last Mar 18, first Nov 18
- Damascus, OR 97089 · last Mar 27, first Nov 14
Frequently asked questions
- When is the last frost in Portland, OR?
- For ZIP code 97233, the average last spring frost (32°F) is March 13, based on NOAA 1991-2020 climate normals for the Portland Wfo, OR weather station. There is a 1-in-10 chance of a frost after April 5.
- When is the first frost in Portland, OR?
- The average first fall frost (32°F) is November 22. There is a 1-in-10 chance of frost by November 3, so tender plants are at risk from that point on.
- How long is the growing season in 97233?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 251 days long.
- Are these frost dates a forecast?
- No. They are 30-year averages and probabilities from NOAA weather station records. Use them to plan, then watch your local forecast before planting tender crops or leaving them uncovered.