Frost dates for 98941Roslyn, WA
The average last spring frost in Roslyn is May 9 and the average first fall frost is October 6, giving a typical growing season of about 151 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 9
- Average first fall frost
- Oct 6
- Growing season
- 151 days
Safer after May 26 (1-in-10 risk)
Possible by Sep 24 (1-in-10 risk)
Last frost typically in 195 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) | May 11 · May 28 · Jun 24 | Sep 10 · Sep 23 · Oct 5 | 115 days | 100% |
| Frost / freeze (32°F) | Apr 25 · May 9 · May 26 | Sep 24 · Oct 6 · Oct 21 | 151 days | 100% |
| Hard freeze (28°F) | Apr 3 · Apr 24 · May 10 | Oct 5 · Oct 20 · Nov 6 | 180 days | 100% |
Planting calendar for Roslyn
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 | Apr 8 – Jun 14 |
| Tomatoes | Transplant outdoors | May 25 – Jun 16 |
| Peppers | Start seeds indoors | Apr 8 – May 9 |
| Peppers | Transplant outdoors | Jun 8 – Jul 9 |
| Eggplant | Start seeds indoors | Apr 25 – May 24 |
| Eggplant | Transplant outdoors | Jun 8 – Jul 9 |
| Cucumbers | Sow outdoors | Jun 8 – Jun 26 |
| Summer squash | Sow outdoors | May 25 – Jul 9 |
| Winter squash & pumpkins | Sow outdoors | Jun 8 – Jul 9 |
| Snap beans | Sow outdoors | May 25 – Jul 19 |
| Sweet corn | Sow outdoors | May 25 – Jun 16 |
| Watermelon & cantaloupe | Sow outdoors | Jun 8 – Jul 9 |
| Okra | Sow outdoors | Jun 1 – Jun 24 |
| Peas | Sow outdoors (spring) | Apr 8 – May 24 |
| Potatoes | Plant outdoors (spring) | Apr 8 – Jun 8 |
| Onions | Start seeds indoors (spring) | Feb 25 – Mar 24 |
| Onions | Transplant outdoors (spring) | Apr 25 – May 24 |
| Broccoli | Start seeds indoors (spring) | Mar 21 – Apr 24 |
| Broccoli | Transplant outdoors (spring) | Apr 25 – May 24 |
| Broccoli | Start seeds indoors (fall) | Jun 6 – Jun 16 |
| Broccoli | Transplant outdoors (fall) | Jul 6 – Jul 17 |
| Cabbage | Start seeds indoors (spring) | Mar 11 – Apr 8 |
| Cabbage | Transplant outdoors (spring) | Apr 8 – May 9 |
| Cabbage | Start seeds indoors (fall) | May 27 – Jun 26 |
| Cabbage | Transplant outdoors (fall) | Jun 26 – Jul 27 |
| Leaf lettuce | Sow outdoors (spring) | Apr 8 – Jun 24 |
| Leaf lettuce | Sow outdoors (fall) | Jun 26 – Aug 12 |
| Spinach | Sow outdoors (spring) | Apr 1 – May 15 |
| Spinach | Sow outdoors (fall) | Jul 13 – Aug 17 |
| Radishes | Sow outdoors (spring) | Apr 8 – May 29 |
| Radishes | Sow outdoors (fall) | Jun 26 – Aug 27 |
| Kale | Sow outdoors (spring) | Apr 25 – May 15 |
| Kale | Sow outdoors (fall) | Jun 19 – Jul 27 |
| Carrots | Sow outdoors (spring) | May 9 – Jun 24 |
| Carrots | Sow outdoors (fall) | May 27 – Jul 12 |
| Garlic | Plant outdoors (fall) | Sep 26 – Oct 27 |
Where these dates come from
ZIP code 98941 is matched to the NOAA station Easton, WA, 14.1 km away, at 2,170 ft elevation (107 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Easton, WA (used) | 2,170 ft | May 9 | Oct 6 |
| Cle Elum, WA | 1,900 ft | May 13 | Sep 25 |
| Stampede Pass, WA | 3,959 ft | May 14 | Oct 17 |
| Ellensburg Bowers Fld, WA | 1,766 ft | Apr 28 | Oct 7 |
Frost dates near Roslyn
- Cle Elum, WA 98922 · last May 13, first Sep 25
- Ronald, WA 98940 · last May 9, first Oct 6
- South Cle Elum, WA 98943 · last May 13, first Sep 25
- Easton, WA 98925 · last May 9, first Oct 6
- Thorp, WA 98946 · last Apr 28, first Oct 7
- Snoqualmie Pass, WA 98068 · last May 14, first Oct 17
- Ellensburg, WA 98926 · last May 8, first Oct 2
- Naches, WA 98937 · last May 9, first Oct 6
Frequently asked questions
- When is the last frost in Roslyn, WA?
- For ZIP code 98941, the average last spring frost (32°F) is May 9, based on NOAA 1991-2020 climate normals for the Easton, WA weather station. There is a 1-in-10 chance of a frost after May 26.
- When is the first frost in Roslyn, WA?
- The average first fall frost (32°F) is October 6. 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 98941?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 151 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.