Frost dates for 97230Portland, 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 97230 is matched to the NOAA station Portland Wfo, OR, 3.3 km away, at 21 ft elevation (61 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 97233 · last Mar 13, first Nov 22
- Fairview, OR 97024 · last Mar 16, first Nov 20
- Vancouver, WA 98683 · last Apr 26, first Oct 18
- Gresham, OR 97030 · last Mar 16, first Nov 20
- Camas, WA 98607 · last Mar 26, first Nov 17
- Troutdale, OR 97060 · last Mar 26, first Nov 17
- Happy Valley, OR 97086 · 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 97230, 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 97230?
- 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.