Frost dates for 98390Sumner, WA
The average last spring frost in Sumner is March 8 and the average first fall frost is November 14, giving a typical growing season of about 250 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Mar 8
- Average first fall frost
- Nov 14
- Growing season
- 250 days
Safer after Mar 31 (1-in-10 risk)
Possible by Oct 30 (1-in-10 risk)
First frost typically in 11 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 13 · Apr 2 · Apr 24 | Oct 16 · Oct 31 · Nov 15 | 209 days | 100% |
| Frost / freeze (32°F) | Feb 15 · Mar 8 · Mar 31 | Oct 30 · Nov 14 · Dec 2 | 250 days | 100% |
| Hard freeze (28°F) | Dec 29 · Feb 11 · Mar 4 | Nov 8 · Dec 1 · Jan 1 | 301 days | 99% |
Planting calendar for Sumner
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 5 – Apr 13 |
| Tomatoes | Transplant outdoors | Mar 24 – Jul 25 |
| Peppers | Start seeds indoors | Feb 5 – Mar 8 |
| Peppers | Transplant outdoors | Apr 7 – May 8 |
| Eggplant | Start seeds indoors | Feb 22 – Mar 23 |
| Eggplant | Transplant outdoors | Apr 7 – May 8 |
| Cucumbers | Sow outdoors | Apr 7 – Aug 4 |
| Summer squash | Sow outdoors | Mar 24 – May 8 |
| Winter squash & pumpkins | Sow outdoors | Apr 7 – May 8 |
| Snap beans | Sow outdoors | Mar 24 – Aug 27 |
| Sweet corn | Sow outdoors | Mar 24 – Jul 25 |
| Watermelon & cantaloupe | Sow outdoors | Apr 7 – May 8 |
| Okra | Sow outdoors | Mar 31 – Apr 23 |
| Peas | Sow outdoors (spring) | Feb 5 – Mar 23 |
| Potatoes | Plant outdoors (spring) | Feb 5 – Apr 7 |
| Onions | Start seeds indoors (spring) | Dec 25 – Jan 21 |
| Onions | Transplant outdoors (spring) | Feb 22 – Mar 23 |
| Broccoli | Start seeds indoors (spring) | Jan 18 – Feb 21 |
| Broccoli | Transplant outdoors (spring) | Feb 22 – Mar 23 |
| Broccoli | Start seeds indoors (fall) | Jul 15 – Jul 25 |
| Broccoli | Transplant outdoors (fall) | Aug 14 – Aug 25 |
| Cabbage | Start seeds indoors (spring) | Jan 8 – Feb 5 |
| Cabbage | Transplant outdoors (spring) | Feb 5 – Mar 8 |
| Cabbage | Start seeds indoors (fall) | Jul 5 – Aug 4 |
| Cabbage | Transplant outdoors (fall) | Aug 4 – Sep 4 |
| Leaf lettuce | Sow outdoors (spring) | Feb 5 – Apr 23 |
| Leaf lettuce | Sow outdoors (fall) | Aug 4 – Sep 20 |
| Spinach | Sow outdoors (spring) | Jan 29 – Mar 14 |
| Spinach | Sow outdoors (fall) | Aug 21 – Sep 25 |
| Radishes | Sow outdoors (spring) | Feb 5 – Mar 28 |
| Radishes | Sow outdoors (fall) | Aug 4 – Oct 5 |
| Kale | Sow outdoors (spring) | Feb 22 – Mar 14 |
| Kale | Sow outdoors (fall) | Jul 28 – Sep 4 |
| Carrots | Sow outdoors (spring) | Mar 8 – Apr 23 |
| Carrots | Sow outdoors (fall) | Jul 5 – Aug 20 |
| Garlic | Plant outdoors (fall) | Nov 4 – Dec 5 |
Where these dates come from
ZIP code 98390 is matched to the NOAA station Tacoma #1, WA, 14.5 km away, at 25 ft elevation (41 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Tacoma #1, WA (used) | 25 ft | Mar 8 | Nov 14 |
| Mcmillin Rsvr, WA | 579 ft | Apr 11 | Oct 30 |
| Buckley 1 Ne, WA | 685 ft | Apr 7 | Oct 30 |
| Kent, WA | 30 ft | Mar 20 | Nov 10 |
Frost dates near Sumner
- Puyallup, WA 98372 · last Mar 8, first Nov 14
- Pacific, WA 98047 · last Mar 8, first Nov 14
- Milton, WA 98354 · last Mar 8, first Nov 14
- Bonney Lake, WA 98391 · last Apr 11, first Oct 30
- Tacoma, WA 98424 · last Mar 8, first Nov 14
- Auburn, WA 98002 · last Mar 20, first Nov 10
- South Prairie, WA 98385 · last Apr 11, first Oct 30
- Federal Way, WA 98003 · last Mar 2, first Nov 23
Frequently asked questions
- When is the last frost in Sumner, WA?
- For ZIP code 98390, the average last spring frost (32°F) is March 8, based on NOAA 1991-2020 climate normals for the Tacoma #1, WA weather station. There is a 1-in-10 chance of a frost after March 31.
- When is the first frost in Sumner, WA?
- The average first fall frost (32°F) is November 14. 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 98390?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 250 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.