Frost dates for 98601Amboy, WA
The average last spring frost in Amboy is April 26 and the average first fall frost is October 16, giving a typical growing season of about 174 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Apr 26
- Average first fall frost
- Oct 16
- Growing season
- 174 days
Safer after May 12 (1-in-10 risk)
Possible by Sep 29 (1-in-10 risk)
Last frost typically in 179 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 29 · May 13 · May 31 | Sep 11 · Sep 30 · Oct 19 | 137 days | 100% |
| Frost / freeze (32°F) | Apr 5 · Apr 26 · May 12 | Sep 29 · Oct 16 · Nov 10 | 174 days | 100% |
| Hard freeze (28°F) | Mar 4 · Mar 29 · Apr 23 | Oct 16 · Nov 5 · Nov 30 | 219 days | 100% |
Planting calendar for Amboy
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 | Mar 26 – Jun 1 |
| Tomatoes | Transplant outdoors | May 12 – Jun 26 |
| Peppers | Start seeds indoors | Mar 26 – Apr 26 |
| Peppers | Transplant outdoors | May 26 – Jun 26 |
| Eggplant | Start seeds indoors | Apr 12 – May 11 |
| Eggplant | Transplant outdoors | May 26 – Jun 26 |
| Cucumbers | Sow outdoors | May 26 – Jul 6 |
| Summer squash | Sow outdoors | May 12 – Jun 26 |
| Winter squash & pumpkins | Sow outdoors | May 26 – Jun 26 |
| Snap beans | Sow outdoors | May 12 – Jul 29 |
| Sweet corn | Sow outdoors | May 12 – Jun 26 |
| Watermelon & cantaloupe | Sow outdoors | May 26 – Jun 26 |
| Okra | Sow outdoors | May 19 – Jun 11 |
| Peas | Sow outdoors (spring) | Mar 26 – May 11 |
| Potatoes | Plant outdoors (spring) | Mar 26 – May 26 |
| Onions | Start seeds indoors (spring) | Feb 12 – Mar 11 |
| Onions | Transplant outdoors (spring) | Apr 12 – May 11 |
| Broccoli | Start seeds indoors (spring) | Mar 8 – Apr 11 |
| Broccoli | Transplant outdoors (spring) | Apr 12 – May 11 |
| Broccoli | Start seeds indoors (fall) | Jun 16 – Jun 26 |
| Broccoli | Transplant outdoors (fall) | Jul 16 – Jul 27 |
| Cabbage | Start seeds indoors (spring) | Feb 26 – Mar 26 |
| Cabbage | Transplant outdoors (spring) | Mar 26 – Apr 26 |
| Cabbage | Start seeds indoors (fall) | Jun 6 – Jul 6 |
| Cabbage | Transplant outdoors (fall) | Jul 6 – Aug 6 |
| Leaf lettuce | Sow outdoors (spring) | Mar 26 – Jun 11 |
| Leaf lettuce | Sow outdoors (fall) | Jul 6 – Aug 22 |
| Spinach | Sow outdoors (spring) | Mar 19 – May 2 |
| Spinach | Sow outdoors (fall) | Jul 23 – Aug 27 |
| Radishes | Sow outdoors (spring) | Mar 26 – May 16 |
| Radishes | Sow outdoors (fall) | Jul 6 – Sep 6 |
| Kale | Sow outdoors (spring) | Apr 12 – May 2 |
| Kale | Sow outdoors (fall) | Jun 29 – Aug 6 |
| Carrots | Sow outdoors (spring) | Apr 26 – Jun 11 |
| Carrots | Sow outdoors (fall) | Jun 6 – Jul 22 |
| Garlic | Plant outdoors (fall) | Oct 6 – Nov 6 |
Where these dates come from
ZIP code 98601 is matched to the NOAA station Battle Ground, WA, 17.3 km away, at 284 ft elevation (96 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Battle Ground, WA (used) | 284 ft | Apr 26 | Oct 16 |
| Cougar 6 E, WA | 659 ft | Apr 1 | Nov 18 |
| Vancouver 4 Nne, WA | 210 ft | Apr 26 | Oct 18 |
| Saint Helens Rfd, OR | 269 ft | Apr 18 | Nov 7 |
Frost dates near Amboy
- Yacolt, WA 98675 · last Apr 1, first Nov 18
- Ariel, WA 98603 · last Apr 1, first Nov 18
- Heisson, WA 98622 · last Apr 26, first Oct 16
- La Center, WA 98629 · last Apr 26, first Oct 16
- Battle Ground, WA 98604 · last Apr 26, first Oct 16
- Cougar, WA 98616 · last Apr 1, first Nov 18
- Woodland, WA 98674 · last Apr 10, first Nov 2
- Brush Prairie, WA 98606 · last Apr 26, first Oct 16
Frequently asked questions
- When is the last frost in Amboy, WA?
- For ZIP code 98601, the average last spring frost (32°F) is April 26, based on NOAA 1991-2020 climate normals for the Battle Ground, WA weather station. There is a 1-in-10 chance of a frost after May 12.
- When is the first frost in Amboy, WA?
- The average first fall frost (32°F) is October 16. There is a 1-in-10 chance of frost by September 29, so tender plants are at risk from that point on.
- How long is the growing season in 98601?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 174 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.