Frost dates for 99023Mica, WA
The average last spring frost in Mica is May 11 and the average first fall frost is October 5, giving a typical growing season of about 143 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 11
- Average first fall frost
- Oct 5
- Growing season
- 143 days
Safer after Jun 4 (1-in-10 risk)
Possible by Sep 15 (1-in-10 risk)
Last frost typically in 197 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 15 · Jun 7 · Jun 24 | Aug 25 · Sep 20 · Oct 7 | 103 days | 100% |
| Frost / freeze (32°F) | Apr 25 · May 11 · Jun 4 | Sep 15 · Oct 5 · Oct 21 | 143 days | 100% |
| Hard freeze (28°F) | Mar 29 · Apr 22 · May 10 | Oct 2 · Oct 19 · Nov 6 | 181 days | 100% |
Planting calendar for Mica
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 10 – Jun 16 |
| Tomatoes | Transplant outdoors | May 27 – Jun 15 |
| Peppers | Start seeds indoors | Apr 10 – May 11 |
| Peppers | Transplant outdoors | Jun 10 – Jul 11 |
| Eggplant | Start seeds indoors | Apr 27 – May 26 |
| Eggplant | Transplant outdoors | Jun 10 – Jul 11 |
| Cucumbers | Sow outdoors | Jun 10 – Jun 25 |
| Summer squash | Sow outdoors | May 27 – Jul 11 |
| Winter squash & pumpkins | Sow outdoors | Jun 10 – Jul 11 |
| Snap beans | Sow outdoors | May 27 – Jul 18 |
| Sweet corn | Sow outdoors | May 27 – Jun 15 |
| Watermelon & cantaloupe | Sow outdoors | Jun 10 – Jul 11 |
| Okra | Sow outdoors | Jun 3 – Jun 26 |
| Peas | Sow outdoors (spring) | Apr 10 – May 26 |
| Potatoes | Plant outdoors (spring) | Apr 10 – Jun 10 |
| Onions | Start seeds indoors (spring) | Feb 27 – Mar 26 |
| Onions | Transplant outdoors (spring) | Apr 27 – May 26 |
| Broccoli | Start seeds indoors (spring) | Mar 23 – Apr 26 |
| Broccoli | Transplant outdoors (spring) | Apr 27 – May 26 |
| Broccoli | Start seeds indoors (fall) | Jun 5 – Jun 15 |
| Broccoli | Transplant outdoors (fall) | Jul 5 – Jul 16 |
| Cabbage | Start seeds indoors (spring) | Mar 13 – Apr 10 |
| Cabbage | Transplant outdoors (spring) | Apr 10 – May 11 |
| Cabbage | Start seeds indoors (fall) | May 26 – Jun 25 |
| Cabbage | Transplant outdoors (fall) | Jun 25 – Jul 26 |
| Leaf lettuce | Sow outdoors (spring) | Apr 10 – Jun 26 |
| Leaf lettuce | Sow outdoors (fall) | Jun 25 – Aug 11 |
| Spinach | Sow outdoors (spring) | Apr 3 – May 17 |
| Spinach | Sow outdoors (fall) | Jul 12 – Aug 16 |
| Radishes | Sow outdoors (spring) | Apr 10 – May 31 |
| Radishes | Sow outdoors (fall) | Jun 25 – Aug 26 |
| Kale | Sow outdoors (spring) | Apr 27 – May 17 |
| Kale | Sow outdoors (fall) | Jun 18 – Jul 26 |
| Carrots | Sow outdoors (spring) | May 11 – Jun 26 |
| Carrots | Sow outdoors (fall) | May 26 – Jul 11 |
| Garlic | Plant outdoors (fall) | Sep 25 – Oct 26 |
Where these dates come from
ZIP code 99023 is matched to the NOAA station Plummer 3 Wsw, ID, 31.2 km away, at 2,905 ft elevation (15 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Plummer 3 Wsw, ID (used) | 2,905 ft | May 11 | Oct 5 |
| Spokane Felts Fld, WA | 1,953 ft | Apr 26 | Oct 15 |
| Spokane Intl Ap, WA | 2,353 ft | Apr 26 | Oct 12 |
| Coeur D'Alene, ID | 2,133 ft | Apr 22 | Oct 18 |
Frost dates near Mica
- Valleyford, WA 99036 · last Apr 26, first Oct 12
- Veradale, WA 99037 · last Apr 26, first Oct 15
- Rockford, WA 99030 · last May 7, first Sep 28
- Greenacres, WA 99016 · last Apr 26, first Oct 15
- Liberty Lake, WA 99019 · last Apr 26, first Oct 15
- Spokane, WA 99206 · last Apr 26, first Oct 15
- Otis Orchards, WA 99027 · last Apr 26, first Oct 15
- Fairfield, WA 99012 · last May 7, first Sep 28
Frequently asked questions
- When is the last frost in Mica, WA?
- For ZIP code 99023, the average last spring frost (32°F) is May 11, based on NOAA 1991-2020 climate normals for the Plummer 3 Wsw, ID weather station. There is a 1-in-10 chance of a frost after June 4.
- When is the first frost in Mica, WA?
- The average first fall frost (32°F) is October 5. There is a 1-in-10 chance of frost by September 15, so tender plants are at risk from that point on.
- How long is the growing season in 99023?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 143 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.