Frost dates for 97086Happy Valley, OR
The average last spring frost in Happy Valley is March 18 and the average first fall frost is November 18, giving a typical growing season of about 244 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Mar 18
- Average first fall frost
- Nov 18
- Growing season
- 244 days
Safer after Apr 11 (1-in-10 risk)
Possible by Oct 30 (1-in-10 risk)
First frost typically in 16 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 26 · Apr 15 · May 4 | Oct 16 · Oct 31 · Nov 20 | 198 days | 100% |
| Frost / freeze (32°F) | Feb 19 · Mar 18 · Apr 11 | Oct 30 · Nov 18 · Dec 12 | 244 days | 100% |
| Hard freeze (28°F) | Jan 1 · Feb 12 · Mar 7 | Nov 16 · Dec 8 · Jan 5 | 302 days | 97% |
Planting calendar for Happy Valley
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 15 – Apr 23 |
| Tomatoes | Transplant outdoors | Apr 3 – Jul 29 |
| Peppers | Start seeds indoors | Feb 15 – Mar 18 |
| Peppers | Transplant outdoors | Apr 17 – May 18 |
| Eggplant | Start seeds indoors | Mar 4 – Apr 2 |
| Eggplant | Transplant outdoors | Apr 17 – May 18 |
| Cucumbers | Sow outdoors | Apr 17 – Aug 8 |
| Summer squash | Sow outdoors | Apr 3 – May 18 |
| Winter squash & pumpkins | Sow outdoors | Apr 17 – May 18 |
| Snap beans | Sow outdoors | Apr 3 – Aug 31 |
| Sweet corn | Sow outdoors | Apr 3 – Jul 29 |
| Watermelon & cantaloupe | Sow outdoors | Apr 17 – May 18 |
| Okra | Sow outdoors | Apr 10 – May 3 |
| Peas | Sow outdoors (spring) | Feb 15 – Apr 2 |
| Potatoes | Plant outdoors (spring) | Feb 15 – Apr 17 |
| Onions | Start seeds indoors (spring) | Jan 4 – Jan 31 |
| Onions | Transplant outdoors (spring) | Mar 4 – Apr 2 |
| Broccoli | Start seeds indoors (spring) | Jan 28 – Mar 3 |
| Broccoli | Transplant outdoors (spring) | Mar 4 – Apr 2 |
| Broccoli | Start seeds indoors (fall) | Jul 19 – Jul 29 |
| Broccoli | Transplant outdoors (fall) | Aug 18 – Aug 29 |
| Cabbage | Start seeds indoors (spring) | Jan 18 – Feb 15 |
| Cabbage | Transplant outdoors (spring) | Feb 15 – Mar 18 |
| Cabbage | Start seeds indoors (fall) | Jul 9 – Aug 8 |
| Cabbage | Transplant outdoors (fall) | Aug 8 – Sep 8 |
| Leaf lettuce | Sow outdoors (spring) | Feb 15 – May 3 |
| Leaf lettuce | Sow outdoors (fall) | Aug 8 – Sep 24 |
| Spinach | Sow outdoors (spring) | Feb 8 – Mar 24 |
| Spinach | Sow outdoors (fall) | Aug 25 – Sep 29 |
| Radishes | Sow outdoors (spring) | Feb 15 – Apr 7 |
| Radishes | Sow outdoors (fall) | Aug 8 – Oct 9 |
| Kale | Sow outdoors (spring) | Mar 4 – Mar 24 |
| Kale | Sow outdoors (fall) | Aug 1 – Sep 8 |
| Carrots | Sow outdoors (spring) | Mar 18 – May 3 |
| Carrots | Sow outdoors (fall) | Jul 9 – Aug 24 |
| Garlic | Plant outdoors (fall) | Nov 8 – Dec 9 |
Where these dates come from
ZIP code 97086 is matched to the NOAA station Oregon City, OR, 11.2 km away, at 167 ft elevation (397 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Oregon City, OR (used) | 167 ft | Mar 18 | Nov 18 |
| Portland Wfo, OR | 21 ft | Mar 13 | Nov 22 |
| Portland Kgw-Tv, OR | 159 ft | Feb 25 | Dec 1 |
| Portland Troutdale Ap, OR | 29 ft | Mar 16 | Nov 20 |
Frost dates near Happy Valley
- Clackamas, OR 97015 · last Mar 18, first Nov 18
- Portland, OR 97266 · last Feb 25, first Dec 1
- Damascus, OR 97089 · last Mar 27, first Nov 14
- Gladstone, OR 97027 · last Mar 18, first Nov 18
- Marylhurst, OR 97036 · last Mar 18, first Nov 18
- Gresham, OR 97080 · last Mar 16, first Nov 20
- Oregon City, OR 97045 · last Mar 18, first Nov 18
- Lake Oswego, OR 97034 · last Mar 18, first Nov 18
Frequently asked questions
- When is the last frost in Happy Valley, OR?
- For ZIP code 97086, the average last spring frost (32°F) is March 18, based on NOAA 1991-2020 climate normals for the Oregon City, OR weather station. There is a 1-in-10 chance of a frost after April 11.
- When is the first frost in Happy Valley, OR?
- The average first fall frost (32°F) is November 18. There is a 1-in-10 chance of frost by October 30, so tender plants are at risk from that point on.
- How long is the growing season in 97086?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 244 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.