Frost dates for 64661Mercer, MO
The average last spring frost in Mercer is April 25 and the average first fall frost is October 15, giving a typical growing season of about 174 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Apr 25
- Average first fall frost
- Oct 15
- Growing season
- 174 days
Safer after May 8 (1-in-10 risk)
Possible by Sep 30 (1-in-10 risk)
Last frost typically in 181 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 20 · May 5 · May 18 | Sep 21 · Oct 5 · Oct 19 | 153 days | 100% |
| Frost / freeze (32°F) | Apr 11 · Apr 25 · May 8 | Sep 30 · Oct 15 · Oct 29 | 174 days | 100% |
| Hard freeze (28°F) | Mar 31 · Apr 14 · Apr 28 | Oct 11 · Oct 26 · Nov 8 | 195 days | 100% |
Planting calendar for Mercer
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 25 – May 31 |
| Tomatoes | Transplant outdoors | May 11 – Jun 25 |
| Peppers | Start seeds indoors | Mar 25 – Apr 25 |
| Peppers | Transplant outdoors | May 25 – Jun 25 |
| Eggplant | Start seeds indoors | Apr 11 – May 10 |
| Eggplant | Transplant outdoors | May 25 – Jun 25 |
| Cucumbers | Sow outdoors | May 25 – Jul 5 |
| Summer squash | Sow outdoors | May 11 – Jun 25 |
| Winter squash & pumpkins | Sow outdoors | May 25 – Jun 25 |
| Snap beans | Sow outdoors | May 11 – Jul 28 |
| Sweet corn | Sow outdoors | May 11 – Jun 25 |
| Watermelon & cantaloupe | Sow outdoors | May 25 – Jun 25 |
| Okra | Sow outdoors | May 18 – Jun 10 |
| Peas | Sow outdoors (spring) | Mar 25 – May 10 |
| Potatoes | Plant outdoors (spring) | Mar 25 – May 25 |
| Onions | Start seeds indoors (spring) | Feb 11 – Mar 10 |
| Onions | Transplant outdoors (spring) | Apr 11 – May 10 |
| Broccoli | Start seeds indoors (spring) | Mar 7 – Apr 10 |
| Broccoli | Transplant outdoors (spring) | Apr 11 – May 10 |
| Broccoli | Start seeds indoors (fall) | Jun 15 – Jun 25 |
| Broccoli | Transplant outdoors (fall) | Jul 15 – Jul 26 |
| Cabbage | Start seeds indoors (spring) | Feb 25 – Mar 25 |
| Cabbage | Transplant outdoors (spring) | Mar 25 – Apr 25 |
| Cabbage | Start seeds indoors (fall) | Jun 5 – Jul 5 |
| Cabbage | Transplant outdoors (fall) | Jul 5 – Aug 5 |
| Leaf lettuce | Sow outdoors (spring) | Mar 25 – Jun 10 |
| Leaf lettuce | Sow outdoors (fall) | Jul 5 – Aug 21 |
| Spinach | Sow outdoors (spring) | Mar 18 – May 1 |
| Spinach | Sow outdoors (fall) | Jul 22 – Aug 26 |
| Radishes | Sow outdoors (spring) | Mar 25 – May 15 |
| Radishes | Sow outdoors (fall) | Jul 5 – Sep 5 |
| Kale | Sow outdoors (spring) | Apr 11 – May 1 |
| Kale | Sow outdoors (fall) | Jun 28 – Aug 5 |
| Carrots | Sow outdoors (spring) | Apr 25 – Jun 10 |
| Carrots | Sow outdoors (fall) | Jun 5 – Jul 21 |
| Garlic | Plant outdoors (fall) | Oct 5 – Nov 5 |
Where these dates come from
ZIP code 64661 is matched to the NOAA station Princeton, MO, 14.1 km away, at 980 ft elevation (40 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Princeton, MO (used) | 980 ft | Apr 25 | Oct 15 |
| Allerton, IA | 1,090 ft | Apr 21 | Oct 19 |
| Leon 6 Ese, IA | 1,000 ft | Apr 30 | Oct 8 |
| Spickard 7 W, MO | 875 ft | Apr 20 | Oct 16 |
Frost dates near Mercer
- Lineville, IA 50147 · last Apr 21, first Oct 19
- Clio, IA 50052 · last Apr 21, first Oct 19
- Princeton, MO 64673 · last Apr 25, first Oct 15
- Powersville, MO 64672 · last Apr 21, first Oct 19
- Cainsville, MO 64632 · last Apr 25, first Oct 15
- Lucerne, MO 64655 · last Apr 25, first Oct 15
- Allerton, IA 50008 · last Apr 21, first Oct 19
- Newtown, MO 64667 · last Apr 25, first Oct 15
Frequently asked questions
- When is the last frost in Mercer, MO?
- For ZIP code 64661, the average last spring frost (32°F) is April 25, based on NOAA 1991-2020 climate normals for the Princeton, MO weather station. There is a 1-in-10 chance of a frost after May 8.
- When is the first frost in Mercer, MO?
- The average first fall frost (32°F) is October 15. There is a 1-in-10 chance of frost by September 30, so tender plants are at risk from that point on.
- How long is the growing season in 64661?
- 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.