Frost dates for 98074Sammamish, WA
The average last spring frost in Sammamish is March 30 and the average first fall frost is November 7, giving a typical growing season of about 223 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Mar 30
- Average first fall frost
- Nov 7
- Growing season
- 223 days
Safer after Apr 21 (1-in-10 risk)
Possible by Oct 22 (1-in-10 risk)
First frost typically in 4 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 8 · Apr 26 · May 13 | Oct 4 · Oct 22 · Nov 7 | 180 days | 100% |
| Frost / freeze (32°F) | Mar 4 · Mar 30 · Apr 21 | Oct 22 · Nov 7 · Dec 1 | 223 days | 100% |
| Hard freeze (28°F) | Jan 16 · Feb 27 · Mar 25 | Nov 6 · Nov 29 · Dec 31 | 277 days | 99% |
Planting calendar for Sammamish
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 27 – May 5 |
| Tomatoes | Transplant outdoors | Apr 15 – Jul 18 |
| Peppers | Start seeds indoors | Feb 27 – Mar 30 |
| Peppers | Transplant outdoors | Apr 29 – May 30 |
| Eggplant | Start seeds indoors | Mar 16 – Apr 14 |
| Eggplant | Transplant outdoors | Apr 29 – May 30 |
| Cucumbers | Sow outdoors | Apr 29 – Jul 28 |
| Summer squash | Sow outdoors | Apr 15 – May 30 |
| Winter squash & pumpkins | Sow outdoors | Apr 29 – May 30 |
| Snap beans | Sow outdoors | Apr 15 – Aug 20 |
| Sweet corn | Sow outdoors | Apr 15 – Jul 18 |
| Watermelon & cantaloupe | Sow outdoors | Apr 29 – May 30 |
| Okra | Sow outdoors | Apr 22 – May 15 |
| Peas | Sow outdoors (spring) | Feb 27 – Apr 14 |
| Potatoes | Plant outdoors (spring) | Feb 27 – Apr 29 |
| Onions | Start seeds indoors (spring) | Jan 16 – Feb 12 |
| Onions | Transplant outdoors (spring) | Mar 16 – Apr 14 |
| Broccoli | Start seeds indoors (spring) | Feb 9 – Mar 15 |
| Broccoli | Transplant outdoors (spring) | Mar 16 – Apr 14 |
| Broccoli | Start seeds indoors (fall) | Jul 8 – Jul 18 |
| Broccoli | Transplant outdoors (fall) | Aug 7 – Aug 18 |
| Cabbage | Start seeds indoors (spring) | Jan 30 – Feb 27 |
| Cabbage | Transplant outdoors (spring) | Feb 27 – Mar 30 |
| Cabbage | Start seeds indoors (fall) | Jun 28 – Jul 28 |
| Cabbage | Transplant outdoors (fall) | Jul 28 – Aug 28 |
| Leaf lettuce | Sow outdoors (spring) | Feb 27 – May 15 |
| Leaf lettuce | Sow outdoors (fall) | Jul 28 – Sep 13 |
| Spinach | Sow outdoors (spring) | Feb 20 – Apr 5 |
| Spinach | Sow outdoors (fall) | Aug 14 – Sep 18 |
| Radishes | Sow outdoors (spring) | Feb 27 – Apr 19 |
| Radishes | Sow outdoors (fall) | Jul 28 – Sep 28 |
| Kale | Sow outdoors (spring) | Mar 16 – Apr 5 |
| Kale | Sow outdoors (fall) | Jul 21 – Aug 28 |
| Carrots | Sow outdoors (spring) | Mar 30 – May 15 |
| Carrots | Sow outdoors (fall) | Jun 28 – Aug 13 |
| Garlic | Plant outdoors (fall) | Oct 28 – Nov 28 |
Where these dates come from
ZIP code 98074 is matched to the NOAA station Snoqualmie Falls, WA, 18.3 km away, at 440 ft elevation (164 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Snoqualmie Falls, WA (used) | 440 ft | Mar 30 | Nov 7 |
| Seattle Sand Pt Wsfo, WA | 60 ft | Mar 8 | Nov 23 |
| Renton Muni Ap, WA | 29 ft | Mar 13 | Nov 16 |
| Seattle Boeing Fld, WA | 20 ft | Mar 13 | Nov 17 |
Frost dates near Sammamish
- Redmond, WA 98053 · last Mar 8, first Nov 23
- Sammamish, WA 98075 · last Mar 30, first Nov 7
- Bellevue, WA 98008 · last Mar 8, first Nov 23
- Issaquah, WA 98029 · last Mar 30, first Nov 7
- Carnation, WA 98014 · last Apr 17, first Oct 23
- Kirkland, WA 98033 · last Mar 8, first Nov 23
- Preston, WA 98050 · last Mar 30, first Nov 7
- Fall City, WA 98024 · last Mar 30, first Nov 7
Frequently asked questions
- When is the last frost in Sammamish, WA?
- For ZIP code 98074, the average last spring frost (32°F) is March 30, based on NOAA 1991-2020 climate normals for the Snoqualmie Falls, WA weather station. There is a 1-in-10 chance of a frost after April 21.
- When is the first frost in Sammamish, WA?
- The average first fall frost (32°F) is November 7. There is a 1-in-10 chance of frost by October 22, so tender plants are at risk from that point on.
- How long is the growing season in 98074?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 223 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.