Frost dates for 98239Coupeville, WA
The average last spring frost in Coupeville is March 17 and the average first fall frost is November 11, giving a typical growing season of about 237 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Mar 17
- Average first fall frost
- Nov 11
- Growing season
- 237 days
Safer after Apr 3 (1-in-10 risk)
Possible by Oct 21 (1-in-10 risk)
First frost typically in 8 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 27 · Apr 13 · Apr 30 | Oct 7 · Oct 27 · Nov 13 | 194 days | 100% |
| Frost / freeze (32°F) | Feb 24 · Mar 17 · Apr 3 | Oct 21 · Nov 11 · Dec 1 | 237 days | 100% |
| Hard freeze (28°F) | Jan 11 · Feb 21 · Mar 12 | Nov 6 · Nov 28 · Dec 30 | 281 days | 99% |
Planting calendar for Coupeville
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 14 – Apr 22 |
| Tomatoes | Transplant outdoors | Apr 2 – Jul 22 |
| Peppers | Start seeds indoors | Feb 14 – Mar 17 |
| Peppers | Transplant outdoors | Apr 16 – May 17 |
| Eggplant | Start seeds indoors | Mar 3 – Apr 1 |
| Eggplant | Transplant outdoors | Apr 16 – May 17 |
| Cucumbers | Sow outdoors | Apr 16 – Aug 1 |
| Summer squash | Sow outdoors | Apr 2 – May 17 |
| Winter squash & pumpkins | Sow outdoors | Apr 16 – May 17 |
| Snap beans | Sow outdoors | Apr 2 – Aug 24 |
| Sweet corn | Sow outdoors | Apr 2 – Jul 22 |
| Watermelon & cantaloupe | Sow outdoors | Apr 16 – May 17 |
| Okra | Sow outdoors | Apr 9 – May 2 |
| Peas | Sow outdoors (spring) | Feb 14 – Apr 1 |
| Potatoes | Plant outdoors (spring) | Feb 14 – Apr 16 |
| Onions | Start seeds indoors (spring) | Jan 3 – Jan 30 |
| Onions | Transplant outdoors (spring) | Mar 3 – Apr 1 |
| Broccoli | Start seeds indoors (spring) | Jan 27 – Mar 2 |
| Broccoli | Transplant outdoors (spring) | Mar 3 – Apr 1 |
| Broccoli | Start seeds indoors (fall) | Jul 12 – Jul 22 |
| Broccoli | Transplant outdoors (fall) | Aug 11 – Aug 22 |
| Cabbage | Start seeds indoors (spring) | Jan 17 – Feb 14 |
| Cabbage | Transplant outdoors (spring) | Feb 14 – Mar 17 |
| Cabbage | Start seeds indoors (fall) | Jul 2 – Aug 1 |
| Cabbage | Transplant outdoors (fall) | Aug 1 – Sep 1 |
| Leaf lettuce | Sow outdoors (spring) | Feb 14 – May 2 |
| Leaf lettuce | Sow outdoors (fall) | Aug 1 – Sep 17 |
| Spinach | Sow outdoors (spring) | Feb 7 – Mar 23 |
| Spinach | Sow outdoors (fall) | Aug 18 – Sep 22 |
| Radishes | Sow outdoors (spring) | Feb 14 – Apr 6 |
| Radishes | Sow outdoors (fall) | Aug 1 – Oct 2 |
| Kale | Sow outdoors (spring) | Mar 3 – Mar 23 |
| Kale | Sow outdoors (fall) | Jul 25 – Sep 1 |
| Carrots | Sow outdoors (spring) | Mar 17 – May 2 |
| Carrots | Sow outdoors (fall) | Jul 2 – Aug 17 |
| Garlic | Plant outdoors (fall) | Nov 1 – Dec 2 |
Where these dates come from
ZIP code 98239 is matched to the NOAA station Coupeville 1 S, WA, 1.5 km away, at 50 ft elevation (9 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Coupeville 1 S, WA (used) | 50 ft | Mar 17 | Nov 11 |
| Port Townsend, WA | 100 ft | Mar 1 | Nov 28 |
| Whidbey Island Nas, WA | 47 ft | Mar 13 | Nov 14 |
| Sequim 2 E, WA | 50 ft | Apr 21 | Oct 20 |
Frost dates near Coupeville
- Oak Harbor, WA 98277 · last Mar 13, first Nov 14
- Camano Island, WA 98282 · last Mar 17, first Nov 11
- Port Townsend, WA 98368 · last Mar 1, first Nov 28
- Greenbank, WA 98253 · last Mar 1, first Nov 28
- Nordland, WA 98358 · last Mar 1, first Nov 28
- Port Hadlock, WA 98339 · last Mar 1, first Nov 28
- Freeland, WA 98249 · last Mar 1, first Nov 28
- Stanwood, WA 98292 · last Mar 17, first Nov 11
Frequently asked questions
- When is the last frost in Coupeville, WA?
- For ZIP code 98239, the average last spring frost (32°F) is March 17, based on NOAA 1991-2020 climate normals for the Coupeville 1 S, WA weather station. There is a 1-in-10 chance of a frost after April 3.
- When is the first frost in Coupeville, WA?
- The average first fall frost (32°F) is November 11. There is a 1-in-10 chance of frost by October 21, so tender plants are at risk from that point on.
- How long is the growing season in 98239?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 237 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.