Frost dates for 99163Pullman, WA
The average last spring frost in Pullman is May 6 and the average first fall frost is September 29, giving a typical growing season of about 143 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 6
- Average first fall frost
- Sep 29
- Growing season
- 143 days
Safer after May 25 (1-in-10 risk)
Possible by Sep 9 (1-in-10 risk)
Last frost typically in 192 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 · Jun 1 · Jul 1 | Aug 24 · Sep 11 · Sep 29 | 99 days | 100% |
| Frost / freeze (32°F) | Apr 22 · May 6 · May 25 | Sep 9 · Sep 29 · Oct 15 | 143 days | 100% |
| Hard freeze (28°F) | Mar 27 · Apr 19 · May 7 | Sep 26 · Oct 12 · Nov 2 | 178 days | 100% |
Planting calendar for Pullman
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 5 – Jun 11 |
| Tomatoes | Transplant outdoors | May 22 – Jun 9 |
| Peppers | Start seeds indoors | Apr 5 – May 6 |
| Peppers | Transplant outdoors | Jun 5 – Jul 6 |
| Eggplant | Start seeds indoors | Apr 22 – May 21 |
| Eggplant | Transplant outdoors | Jun 5 – Jul 6 |
| Cucumbers | Sow outdoors | Jun 5 – Jun 19 |
| Summer squash | Sow outdoors | May 22 – Jul 6 |
| Winter squash & pumpkins | Sow outdoors | Jun 5 – Jul 6 |
| Snap beans | Sow outdoors | May 22 – Jul 12 |
| Sweet corn | Sow outdoors | May 22 – Jun 9 |
| Watermelon & cantaloupe | Sow outdoors | Jun 5 – Jul 6 |
| Okra | Sow outdoors | May 29 – Jun 21 |
| Peas | Sow outdoors (spring) | Apr 5 – May 21 |
| Potatoes | Plant outdoors (spring) | Apr 5 – Jun 5 |
| Onions | Start seeds indoors (spring) | Feb 22 – Mar 21 |
| Onions | Transplant outdoors (spring) | Apr 22 – May 21 |
| Broccoli | Start seeds indoors (spring) | Mar 18 – Apr 21 |
| Broccoli | Transplant outdoors (spring) | Apr 22 – May 21 |
| Broccoli | Start seeds indoors (fall) | May 30 – Jun 9 |
| Broccoli | Transplant outdoors (fall) | Jun 29 – Jul 10 |
| Cabbage | Start seeds indoors (spring) | Mar 8 – Apr 5 |
| Cabbage | Transplant outdoors (spring) | Apr 5 – May 6 |
| Cabbage | Start seeds indoors (fall) | May 20 – Jun 19 |
| Cabbage | Transplant outdoors (fall) | Jun 19 – Jul 20 |
| Leaf lettuce | Sow outdoors (spring) | Apr 5 – Jun 21 |
| Leaf lettuce | Sow outdoors (fall) | Jun 19 – Aug 5 |
| Spinach | Sow outdoors (spring) | Mar 29 – May 12 |
| Spinach | Sow outdoors (fall) | Jul 6 – Aug 10 |
| Radishes | Sow outdoors (spring) | Apr 5 – May 26 |
| Radishes | Sow outdoors (fall) | Jun 19 – Aug 20 |
| Kale | Sow outdoors (spring) | Apr 22 – May 12 |
| Kale | Sow outdoors (fall) | Jun 12 – Jul 20 |
| Carrots | Sow outdoors (spring) | May 6 – Jun 21 |
| Carrots | Sow outdoors (fall) | May 20 – Jul 5 |
| Garlic | Plant outdoors (fall) | Sep 19 – Oct 20 |
Where these dates come from
ZIP code 99163 is matched to the NOAA station Pullman 2 Nw, WA, 3 km away, at 2,515 ft elevation (35 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Pullman 2 Nw, WA (used) | 2,515 ft | May 6 | Sep 29 |
| Pullman Moscow Rgnl Ap, WA | 2,551 ft | Apr 29 | Oct 2 |
| Moscow U Of I, ID | 2,660 ft | — | — |
| Potlatch 3 Nne, ID | 2,760 ft | May 15 | Sep 21 |
Frost dates near Pullman
- Pullman, WA 99164 · last May 6, first Sep 29
- Albion, WA 99102 · last May 6, first Sep 29
- Moscow, ID 83844 · last —, first —
- Colton, WA 99113 · last Apr 29, first Oct 2
- Palouse, WA 99161 · last May 6, first Sep 29
- Viola, ID 83872 · last May 15, first Sep 21
- Colfax, WA 99111 · last Apr 29, first Oct 4
- Uniontown, WA 99179 · last —, first —
Frequently asked questions
- When is the last frost in Pullman, WA?
- For ZIP code 99163, the average last spring frost (32°F) is May 6, based on NOAA 1991-2020 climate normals for the Pullman 2 Nw, WA weather station. There is a 1-in-10 chance of a frost after May 25.
- When is the first frost in Pullman, WA?
- The average first fall frost (32°F) is September 29. There is a 1-in-10 chance of frost by September 9, so tender plants are at risk from that point on.
- How long is the growing season in 99163?
- 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.