Frost dates for 99022Medical Lake, WA
The average last spring frost in Medical Lake is May 10 and the average first fall frost is September 26, giving a typical growing season of about 137 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 10
- Average first fall frost
- Sep 26
- Growing season
- 137 days
Safer after May 30 (1-in-10 risk)
Possible by Sep 11 (1-in-10 risk)
Last frost typically in 188 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 12 · May 31 · Jun 24 | Aug 29 · Sep 12 · Sep 27 | 103 days | 100% |
| Frost / freeze (32°F) | Apr 25 · May 10 · May 30 | Sep 11 · Sep 26 · Oct 8 | 137 days | 100% |
| Hard freeze (28°F) | Apr 4 · Apr 25 · May 11 | Sep 25 · Oct 7 · Oct 23 | 166 days | 100% |
Planting calendar for Medical Lake
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 9 – Jun 15 |
| Tomatoes | Transplant outdoors | May 26 – Jun 6 |
| Peppers | Start seeds indoors | Apr 9 – May 10 |
| Peppers | Transplant outdoors | Jun 9 – Jul 10 |
| Eggplant | Start seeds indoors | Apr 26 – May 25 |
| Eggplant | Transplant outdoors | Jun 9 – Jul 10 |
| Cucumbers | Sow outdoors | Jun 9 – Jun 16 |
| Summer squash | Sow outdoors | May 26 – Jul 10 |
| Winter squash & pumpkins | Sow outdoors | Jun 9 – Jul 10 |
| Snap beans | Sow outdoors | May 26 – Jul 9 |
| Sweet corn | Sow outdoors | May 26 – Jun 6 |
| Watermelon & cantaloupe | Sow outdoors | Jun 9 – Jul 10 |
| Okra | Sow outdoors | Jun 2 – Jun 25 |
| Peas | Sow outdoors (spring) | Apr 9 – May 25 |
| Potatoes | Plant outdoors (spring) | Apr 9 – Jun 9 |
| Onions | Start seeds indoors (spring) | Feb 26 – Mar 25 |
| Onions | Transplant outdoors (spring) | Apr 26 – May 25 |
| Broccoli | Start seeds indoors (spring) | Mar 22 – Apr 25 |
| Broccoli | Transplant outdoors (spring) | Apr 26 – May 25 |
| Broccoli | Start seeds indoors (fall) | May 27 – Jun 6 |
| Broccoli | Transplant outdoors (fall) | Jun 26 – Jul 7 |
| Cabbage | Start seeds indoors (spring) | Mar 12 – Apr 9 |
| Cabbage | Transplant outdoors (spring) | Apr 9 – May 10 |
| Cabbage | Start seeds indoors (fall) | May 17 – Jun 16 |
| Cabbage | Transplant outdoors (fall) | Jun 16 – Jul 17 |
| Leaf lettuce | Sow outdoors (spring) | Apr 9 – Jun 25 |
| Leaf lettuce | Sow outdoors (fall) | Jun 16 – Aug 2 |
| Spinach | Sow outdoors (spring) | Apr 2 – May 16 |
| Spinach | Sow outdoors (fall) | Jul 3 – Aug 7 |
| Radishes | Sow outdoors (spring) | Apr 9 – May 30 |
| Radishes | Sow outdoors (fall) | Jun 16 – Aug 17 |
| Kale | Sow outdoors (spring) | Apr 26 – May 16 |
| Kale | Sow outdoors (fall) | Jun 9 – Jul 17 |
| Carrots | Sow outdoors (spring) | May 10 – Jun 25 |
| Carrots | Sow outdoors (fall) | May 17 – Jul 2 |
| Garlic | Plant outdoors (fall) | Sep 16 – Oct 17 |
Where these dates come from
ZIP code 99022 is matched to the NOAA station Spokane Wfo, WA, 9.4 km away, at 2,392 ft elevation (65 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Spokane Wfo, WA (used) | 2,392 ft | May 10 | Sep 26 |
| Spokane Intl Ap, WA | 2,353 ft | Apr 26 | Oct 12 |
| Spokane 17 Ssw, WA | 2,267 ft | May 30 | Sep 4 |
| Spokane Felts Fld, WA | 1,953 ft | Apr 26 | Oct 15 |
Frost dates near Medical Lake
- Fairchild Air Force Base, WA 99011 · last May 10, first Sep 26
- Airway Heights, WA 99001 · last May 10, first Sep 26
- Four Lakes, WA 99014 · last Apr 26, first Oct 12
- Spokane, WA 99224 · last Apr 26, first Oct 12
- Reardan, WA 99029 · last May 10, first Sep 26
- Cheney, WA 99004 · last Apr 26, first Oct 12
- Marshall, WA 99020 · last Apr 26, first Oct 12
- Edwall, WA 99008 · last Jun 6, first Sep 11
Frequently asked questions
- When is the last frost in Medical Lake, WA?
- For ZIP code 99022, the average last spring frost (32°F) is May 10, based on NOAA 1991-2020 climate normals for the Spokane Wfo, WA weather station. There is a 1-in-10 chance of a frost after May 30.
- When is the first frost in Medical Lake, WA?
- The average first fall frost (32°F) is September 26. There is a 1-in-10 chance of frost by September 11, so tender plants are at risk from that point on.
- How long is the growing season in 99022?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 137 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.