Frost dates for 98356Morton, WA
The average last spring frost in Morton is April 24 and the average first fall frost is October 15, giving a typical growing season of about 176 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Apr 24
- Average first fall frost
- Oct 15
- Growing season
- 176 days
Safer after May 12 (1-in-10 risk)
Possible by Sep 24 (1-in-10 risk)
Last frost typically in 176 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) | Apr 27 · May 13 · May 31 | Sep 5 · Sep 25 · Oct 16 | 135 days | 100% |
| Frost / freeze (32°F) | Mar 31 · Apr 24 · May 12 | Sep 24 · Oct 15 · Nov 8 | 176 days | 100% |
| Hard freeze (28°F) | Feb 27 · Mar 26 · Apr 18 | Oct 13 · Nov 5 · Nov 26 | 224 days | 100% |
Planting calendar for Morton
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 | Mar 24 – May 30 |
| Tomatoes | Transplant outdoors | May 10 – Jun 25 |
| Peppers | Start seeds indoors | Mar 24 – Apr 24 |
| Peppers | Transplant outdoors | May 24 – Jun 24 |
| Eggplant | Start seeds indoors | Apr 10 – May 9 |
| Eggplant | Transplant outdoors | May 24 – Jun 24 |
| Cucumbers | Sow outdoors | May 24 – Jul 5 |
| Summer squash | Sow outdoors | May 10 – Jun 24 |
| Winter squash & pumpkins | Sow outdoors | May 24 – Jun 24 |
| Snap beans | Sow outdoors | May 10 – Jul 28 |
| Sweet corn | Sow outdoors | May 10 – Jun 25 |
| Watermelon & cantaloupe | Sow outdoors | May 24 – Jun 24 |
| Okra | Sow outdoors | May 17 – Jun 9 |
| Peas | Sow outdoors (spring) | Mar 24 – May 9 |
| Potatoes | Plant outdoors (spring) | Mar 24 – May 24 |
| Onions | Start seeds indoors (spring) | Feb 10 – Mar 9 |
| Onions | Transplant outdoors (spring) | Apr 10 – May 9 |
| Broccoli | Start seeds indoors (spring) | Mar 6 – Apr 9 |
| Broccoli | Transplant outdoors (spring) | Apr 10 – May 9 |
| Broccoli | Start seeds indoors (fall) | Jun 15 – Jun 25 |
| Broccoli | Transplant outdoors (fall) | Jul 15 – Jul 26 |
| Cabbage | Start seeds indoors (spring) | Feb 24 – Mar 24 |
| Cabbage | Transplant outdoors (spring) | Mar 24 – Apr 24 |
| Cabbage | Start seeds indoors (fall) | Jun 5 – Jul 5 |
| Cabbage | Transplant outdoors (fall) | Jul 5 – Aug 5 |
| Leaf lettuce | Sow outdoors (spring) | Mar 24 – Jun 9 |
| Leaf lettuce | Sow outdoors (fall) | Jul 5 – Aug 21 |
| Spinach | Sow outdoors (spring) | Mar 17 – Apr 30 |
| Spinach | Sow outdoors (fall) | Jul 22 – Aug 26 |
| Radishes | Sow outdoors (spring) | Mar 24 – May 14 |
| Radishes | Sow outdoors (fall) | Jul 5 – Sep 5 |
| Kale | Sow outdoors (spring) | Apr 10 – Apr 30 |
| Kale | Sow outdoors (fall) | Jun 28 – Aug 5 |
| Carrots | Sow outdoors (spring) | Apr 24 – Jun 9 |
| Carrots | Sow outdoors (fall) | Jun 5 – Jul 21 |
| Garlic | Plant outdoors (fall) | Oct 5 – Nov 5 |
Where these dates come from
ZIP code 98356 is matched to the NOAA station Glenoma, WA, 9.6 km away, at 840 ft elevation (669 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Glenoma, WA (used) | 840 ft | Apr 24 | Oct 15 |
| Mayfield Pwr Plt, WA | 280 ft | Apr 7 | Nov 13 |
| Longmire Rainier Nps, WA | 2,762 ft | May 22 | Oct 3 |
| Toledo Faa Ap, WA | 379 ft | Apr 5 | Oct 25 |
Frost dates near Morton
- Glenoma, WA 98336 · last Apr 24, first Oct 15
- Silver Creek, WA 98585 · last Apr 5, first Oct 25
- Mineral, WA 98355 · last Apr 18, first Oct 31
- Mossyrock, WA 98564 · last Apr 24, first Oct 15
- Cinebar, WA 98533 · last Apr 5, first Oct 25
- Elbe, WA 98330 · last May 22, first Oct 3
- Salkum, WA 98582 · last Apr 5, first Oct 25
- Ashford, WA 98304 · last May 22, first Oct 3
Frequently asked questions
- When is the last frost in Morton, WA?
- For ZIP code 98356, the average last spring frost (32°F) is April 24, based on NOAA 1991-2020 climate normals for the Glenoma, WA weather station. There is a 1-in-10 chance of a frost after May 12.
- When is the first frost in Morton, WA?
- The average first fall frost (32°F) is October 15. There is a 1-in-10 chance of frost by September 24, so tender plants are at risk from that point on.
- How long is the growing season in 98356?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 176 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.