Frost dates for 42259Mammoth Cave, KY
The average last spring frost in Mammoth Cave is April 22 and the average first fall frost is October 22, giving a typical growing season of about 182 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Apr 22
- Average first fall frost
- Oct 22
- Growing season
- 182 days
Safer after May 11 (1-in-10 risk)
Possible by Oct 9 (1-in-10 risk)
Last frost typically in 170 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 16 · May 2 · May 19 | Sep 30 · Oct 12 · Oct 25 | 161 days | 100% |
| Frost / freeze (32°F) | Apr 5 · Apr 22 · May 11 | Oct 9 · Oct 22 · Nov 3 | 182 days | 100% |
| Hard freeze (28°F) | Mar 23 · Apr 8 · Apr 27 | Oct 19 · Nov 1 · Nov 15 | 205 days | 100% |
Planting calendar for Mammoth Cave
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 22 – May 28 |
| Tomatoes | Transplant outdoors | May 8 – Jul 2 |
| Peppers | Start seeds indoors | Mar 22 – Apr 22 |
| Peppers | Transplant outdoors | May 22 – Jun 22 |
| Eggplant | Start seeds indoors | Apr 8 – May 7 |
| Eggplant | Transplant outdoors | May 22 – Jun 22 |
| Cucumbers | Sow outdoors | May 22 – Jul 12 |
| Summer squash | Sow outdoors | May 8 – Jun 22 |
| Winter squash & pumpkins | Sow outdoors | May 22 – Jun 22 |
| Snap beans | Sow outdoors | May 8 – Aug 4 |
| Sweet corn | Sow outdoors | May 8 – Jul 2 |
| Watermelon & cantaloupe | Sow outdoors | May 22 – Jun 22 |
| Okra | Sow outdoors | May 15 – Jun 7 |
| Peas | Sow outdoors (spring) | Mar 22 – May 7 |
| Potatoes | Plant outdoors (spring) | Mar 22 – May 22 |
| Onions | Start seeds indoors (spring) | Feb 8 – Mar 7 |
| Onions | Transplant outdoors (spring) | Apr 8 – May 7 |
| Broccoli | Start seeds indoors (spring) | Mar 4 – Apr 7 |
| Broccoli | Transplant outdoors (spring) | Apr 8 – May 7 |
| Broccoli | Start seeds indoors (fall) | Jun 22 – Jul 2 |
| Broccoli | Transplant outdoors (fall) | Jul 22 – Aug 2 |
| Cabbage | Start seeds indoors (spring) | Feb 22 – Mar 22 |
| Cabbage | Transplant outdoors (spring) | Mar 22 – Apr 22 |
| Cabbage | Start seeds indoors (fall) | Jun 12 – Jul 12 |
| Cabbage | Transplant outdoors (fall) | Jul 12 – Aug 12 |
| Leaf lettuce | Sow outdoors (spring) | Mar 22 – Jun 7 |
| Leaf lettuce | Sow outdoors (fall) | Jul 12 – Aug 28 |
| Spinach | Sow outdoors (spring) | Mar 15 – Apr 28 |
| Spinach | Sow outdoors (fall) | Jul 29 – Sep 2 |
| Radishes | Sow outdoors (spring) | Mar 22 – May 12 |
| Radishes | Sow outdoors (fall) | Jul 12 – Sep 12 |
| Kale | Sow outdoors (spring) | Apr 8 – Apr 28 |
| Kale | Sow outdoors (fall) | Jul 5 – Aug 12 |
| Carrots | Sow outdoors (spring) | Apr 22 – Jun 7 |
| Carrots | Sow outdoors (fall) | Jun 12 – Jul 28 |
| Garlic | Plant outdoors (fall) | Oct 12 – Nov 12 |
Where these dates come from
ZIP code 42259 is matched to the NOAA station Nolin Rvr Lake, KY, 7.2 km away, at 623 ft elevation (46 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Nolin Rvr Lake, KY (used) | 623 ft | Apr 22 | Oct 22 |
| Bowling Green 21 Nne, KY | 790 ft | Apr 4 | Oct 31 |
| Mammoth Cave, KY | 760 ft | Apr 9 | Oct 30 |
| Millerstown 4E, KY | 600 ft | Apr 21 | Oct 18 |
Frost dates near Mammoth Cave
- Cub Run, KY 42729 · last Apr 4, first Oct 31
- Bee Spring, KY 42207 · last Apr 22, first Oct 22
- Sweeden, KY 42285 · last Apr 22, first Oct 22
- Brownsville, KY 42210 · last Apr 22, first Oct 22
- Clarkson, KY 42726 · last Apr 26, first Oct 15
- Roundhill, KY 42275 · last Apr 22, first Oct 22
- Munfordville, KY 42765 · last Apr 9, first Oct 30
- Park City, KY 42160 · last Apr 9, first Oct 30
Frequently asked questions
- When is the last frost in Mammoth Cave, KY?
- For ZIP code 42259, the average last spring frost (32°F) is April 22, based on NOAA 1991-2020 climate normals for the Nolin Rvr Lake, KY weather station. There is a 1-in-10 chance of a frost after May 11.
- When is the first frost in Mammoth Cave, KY?
- The average first fall frost (32°F) is October 22. There is a 1-in-10 chance of frost by October 9, so tender plants are at risk from that point on.
- How long is the growing season in 42259?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 182 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.