Frost dates for 97203Portland, OR
The average last spring frost in Portland is February 25 and the average first fall frost is December 1, giving a typical growing season of about 280 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Feb 25
- Average first fall frost
- Dec 1
- Growing season
- 280 days
Safer after Mar 21 (1-in-10 risk)
Possible by Nov 10 (1-in-10 risk)
First frost typically in 31 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 7 · Mar 29 · Apr 21 | Oct 28 · Nov 12 · Dec 1 | 227 days | 100% |
| Frost / freeze (32°F) | Jan 24 · Feb 25 · Mar 21 | Nov 10 · Dec 1 · Dec 27 | 280 days | 100% |
| Hard freeze (28°F) | Dec 21 · Jan 31 · Feb 26 | Nov 25 · Dec 20 · Jan 30 | 329 days | 86% |
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 | Jan 25 – Apr 2 |
| Tomatoes | Transplant outdoors | Mar 13 – Aug 11 |
| Peppers | Start seeds indoors | Jan 25 – Feb 25 |
| Peppers | Transplant outdoors | Mar 27 – Apr 27 |
| Eggplant | Start seeds indoors | Feb 11 – Mar 12 |
| Eggplant | Transplant outdoors | Mar 27 – Apr 27 |
| Cucumbers | Sow outdoors | Mar 27 – Aug 21 |
| Summer squash | Sow outdoors | Mar 13 – Apr 27 |
| Winter squash & pumpkins | Sow outdoors | Mar 27 – Apr 27 |
| Snap beans | Sow outdoors | Mar 13 – Sep 13 |
| Sweet corn | Sow outdoors | Mar 13 – Aug 11 |
| Watermelon & cantaloupe | Sow outdoors | Mar 27 – Apr 27 |
| Okra | Sow outdoors | Mar 20 – Apr 12 |
| Peas | Sow outdoors (spring) | Jan 25 – Mar 12 |
| Potatoes | Plant outdoors (spring) | Jan 25 – Mar 27 |
| Onions | Start seeds indoors (spring) | Dec 14 – Jan 10 |
| Onions | Transplant outdoors (spring) | Feb 11 – Mar 12 |
| Broccoli | Start seeds indoors (spring) | Jan 7 – Feb 10 |
| Broccoli | Transplant outdoors (spring) | Feb 11 – Mar 12 |
| Broccoli | Start seeds indoors (fall) | Aug 1 – Aug 11 |
| Broccoli | Transplant outdoors (fall) | Aug 31 – Sep 11 |
| Cabbage | Start seeds indoors (spring) | Dec 28 – Jan 25 |
| Cabbage | Transplant outdoors (spring) | Jan 25 – Feb 25 |
| Cabbage | Start seeds indoors (fall) | Jul 22 – Aug 21 |
| Cabbage | Transplant outdoors (fall) | Aug 21 – Sep 21 |
| Leaf lettuce | Sow outdoors (spring) | Jan 25 – Apr 12 |
| Leaf lettuce | Sow outdoors (fall) | Aug 21 – Oct 7 |
| Spinach | Sow outdoors (spring) | Jan 18 – Mar 3 |
| Spinach | Sow outdoors (fall) | Sep 7 – Oct 12 |
| Radishes | Sow outdoors (spring) | Jan 25 – Mar 17 |
| Radishes | Sow outdoors (fall) | Aug 21 – Oct 22 |
| Kale | Sow outdoors (spring) | Feb 11 – Mar 3 |
| Kale | Sow outdoors (fall) | Aug 14 – Sep 21 |
| Carrots | Sow outdoors (spring) | Feb 25 – Apr 12 |
| Carrots | Sow outdoors (fall) | Jul 22 – Sep 6 |
| Garlic | Plant outdoors (fall) | Nov 21 – Dec 22 |
Where these dates come from
ZIP code 97203 is matched to the NOAA station Portland Kgw-Tv, OR, 8.6 km away, at 159 ft elevation (28 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Portland Kgw-Tv, OR (used) | 159 ft | Feb 25 | Dec 1 |
| Vancouver Pearson Ap, WA | 30 ft | Mar 29 | Nov 9 |
| Portland Intl Ap, OR | 19 ft | Mar 13 | Nov 19 |
| Vancouver 4 Nne, WA | 210 ft | Apr 26 | Oct 18 |
Frost dates near Portland
- Portland, OR 97217 · last Feb 25, first Dec 1
- Vancouver, WA 98660 · last Mar 29, first Nov 9
- Beaverton, OR 97005 · last Apr 1, first Nov 6
- Hillsboro, OR 97124 · last Apr 16, first Oct 23
- Lake Oswego, OR 97035 · last Apr 1, first Nov 6
- Marylhurst, OR 97036 · last Mar 18, first Nov 18
- Ridgefield, WA 98642 · last Apr 26, first Oct 16
- Happy Valley, OR 97086 · last Mar 18, first Nov 18
Frequently asked questions
- When is the last frost in Portland, OR?
- For ZIP code 97203, the average last spring frost (32°F) is February 25, based on NOAA 1991-2020 climate normals for the Portland Kgw-Tv, OR weather station. There is a 1-in-10 chance of a frost after March 21.
- When is the first frost in Portland, OR?
- The average first fall frost (32°F) is December 1. There is a 1-in-10 chance of frost by November 10, so tender plants are at risk from that point on.
- How long is the growing season in 97203?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 280 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.