Frost dates for 66067Ottawa, KS
The average last spring frost in Ottawa is April 18 and the average first fall frost is October 20, giving a typical growing season of about 183 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Apr 18
- Average first fall frost
- Oct 20
- Growing season
- 183 days
Safer after May 1 (1-in-10 risk)
Possible by Oct 3 (1-in-10 risk)
Last frost typically in 173 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 15 · Apr 29 · May 10 | Sep 26 · Oct 9 · Oct 22 | 162 days | 100% |
| Frost / freeze (32°F) | Apr 5 · Apr 18 · May 1 | Oct 3 · Oct 20 · Nov 1 | 183 days | 100% |
| Hard freeze (28°F) | Mar 24 · Apr 8 · Apr 22 | Oct 16 · Oct 30 · Nov 11 | 203 days | 100% |
Planting calendar for Ottawa
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 18 – May 24 |
| Tomatoes | Transplant outdoors | May 4 – Jun 30 |
| Peppers | Start seeds indoors | Mar 18 – Apr 18 |
| Peppers | Transplant outdoors | May 18 – Jun 18 |
| Eggplant | Start seeds indoors | Apr 4 – May 3 |
| Eggplant | Transplant outdoors | May 18 – Jun 18 |
| Cucumbers | Sow outdoors | May 18 – Jul 10 |
| Summer squash | Sow outdoors | May 4 – Jun 18 |
| Winter squash & pumpkins | Sow outdoors | May 18 – Jun 18 |
| Snap beans | Sow outdoors | May 4 – Aug 2 |
| Sweet corn | Sow outdoors | May 4 – Jun 30 |
| Watermelon & cantaloupe | Sow outdoors | May 18 – Jun 18 |
| Okra | Sow outdoors | May 11 – Jun 3 |
| Peas | Sow outdoors (spring) | Mar 18 – May 3 |
| Potatoes | Plant outdoors (spring) | Mar 18 – May 18 |
| Onions | Start seeds indoors (spring) | Feb 4 – Mar 3 |
| Onions | Transplant outdoors (spring) | Apr 4 – May 3 |
| Broccoli | Start seeds indoors (spring) | Feb 28 – Apr 3 |
| Broccoli | Transplant outdoors (spring) | Apr 4 – May 3 |
| Broccoli | Start seeds indoors (fall) | Jun 20 – Jun 30 |
| Broccoli | Transplant outdoors (fall) | Jul 20 – Jul 31 |
| Cabbage | Start seeds indoors (spring) | Feb 18 – Mar 18 |
| Cabbage | Transplant outdoors (spring) | Mar 18 – Apr 18 |
| Cabbage | Start seeds indoors (fall) | Jun 10 – Jul 10 |
| Cabbage | Transplant outdoors (fall) | Jul 10 – Aug 10 |
| Leaf lettuce | Sow outdoors (spring) | Mar 18 – Jun 3 |
| Leaf lettuce | Sow outdoors (fall) | Jul 10 – Aug 26 |
| Spinach | Sow outdoors (spring) | Mar 11 – Apr 24 |
| Spinach | Sow outdoors (fall) | Jul 27 – Aug 31 |
| Radishes | Sow outdoors (spring) | Mar 18 – May 8 |
| Radishes | Sow outdoors (fall) | Jul 10 – Sep 10 |
| Kale | Sow outdoors (spring) | Apr 4 – Apr 24 |
| Kale | Sow outdoors (fall) | Jul 3 – Aug 10 |
| Carrots | Sow outdoors (spring) | Apr 18 – Jun 3 |
| Carrots | Sow outdoors (fall) | Jun 10 – Jul 26 |
| Garlic | Plant outdoors (fall) | Oct 10 – Nov 10 |
Where these dates come from
ZIP code 66067 is matched to the NOAA station Ottawa, KS, 0.6 km away, at 905 ft elevation (7 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Ottawa, KS (used) | 905 ft | Apr 18 | Oct 20 |
| Pomona Lake, KS | 1,063 ft | Apr 8 | Oct 31 |
| Osawatomie, KS | 860 ft | Apr 14 | Oct 25 |
| Hillsdale Lake, KS | 1,010 ft | Apr 9 | Oct 31 |
Frost dates near Ottawa
- Rantoul, KS 66079 · last Apr 18, first Oct 20
- Princeton, KS 66078 · last Apr 18, first Oct 20
- Pomona, KS 66076 · last Apr 8, first Oct 31
- Williamsburg, KS 66095 · last Apr 8, first Oct 31
- Wellsville, KS 66092 · last Apr 9, first Oct 31
- Baldwin City, KS 66006 · last Apr 12, first Oct 28
- Quenemo, KS 66528 · last Apr 8, first Oct 31
- Richmond, KS 66080 · last Apr 17, first Oct 22
Frequently asked questions
- When is the last frost in Ottawa, KS?
- For ZIP code 66067, the average last spring frost (32°F) is April 18, based on NOAA 1991-2020 climate normals for the Ottawa, KS weather station. There is a 1-in-10 chance of a frost after May 1.
- When is the first frost in Ottawa, KS?
- The average first fall frost (32°F) is October 20. There is a 1-in-10 chance of frost by October 3, so tender plants are at risk from that point on.
- How long is the growing season in 66067?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 183 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.