Frost dates for 49045Decatur, MI
The average last spring frost in Decatur is May 4 and the average first fall frost is October 11, giving a typical growing season of about 158 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 4
- Average first fall frost
- Oct 11
- Growing season
- 158 days
Safer after May 22 (1-in-10 risk)
Possible by Sep 27 (1-in-10 risk)
Last frost typically in 183 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 30 · May 15 · May 31 | Sep 15 · Sep 30 · Oct 13 | 136 days | 100% |
| Frost / freeze (32°F) | Apr 21 · May 4 · May 22 | Sep 27 · Oct 11 · Oct 27 | 158 days | 100% |
| Hard freeze (28°F) | Apr 10 · Apr 24 · May 10 | Oct 8 · Oct 26 · Nov 7 | 181 days | 100% |
Planting calendar for Decatur
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 3 – Jun 9 |
| Tomatoes | Transplant outdoors | May 20 – Jun 21 |
| Peppers | Start seeds indoors | Apr 3 – May 4 |
| Peppers | Transplant outdoors | Jun 3 – Jul 4 |
| Eggplant | Start seeds indoors | Apr 20 – May 19 |
| Eggplant | Transplant outdoors | Jun 3 – Jul 4 |
| Cucumbers | Sow outdoors | Jun 3 – Jul 1 |
| Summer squash | Sow outdoors | May 20 – Jul 4 |
| Winter squash & pumpkins | Sow outdoors | Jun 3 – Jul 4 |
| Snap beans | Sow outdoors | May 20 – Jul 24 |
| Sweet corn | Sow outdoors | May 20 – Jun 21 |
| Watermelon & cantaloupe | Sow outdoors | Jun 3 – Jul 4 |
| Okra | Sow outdoors | May 27 – Jun 19 |
| Peas | Sow outdoors (spring) | Apr 3 – May 19 |
| Potatoes | Plant outdoors (spring) | Apr 3 – Jun 3 |
| Onions | Start seeds indoors (spring) | Feb 20 – Mar 19 |
| Onions | Transplant outdoors (spring) | Apr 20 – May 19 |
| Broccoli | Start seeds indoors (spring) | Mar 16 – Apr 19 |
| Broccoli | Transplant outdoors (spring) | Apr 20 – May 19 |
| Broccoli | Start seeds indoors (fall) | Jun 11 – Jun 21 |
| Broccoli | Transplant outdoors (fall) | Jul 11 – Jul 22 |
| Cabbage | Start seeds indoors (spring) | Mar 6 – Apr 3 |
| Cabbage | Transplant outdoors (spring) | Apr 3 – May 4 |
| Cabbage | Start seeds indoors (fall) | Jun 1 – Jul 1 |
| Cabbage | Transplant outdoors (fall) | Jul 1 – Aug 1 |
| Leaf lettuce | Sow outdoors (spring) | Apr 3 – Jun 19 |
| Leaf lettuce | Sow outdoors (fall) | Jul 1 – Aug 17 |
| Spinach | Sow outdoors (spring) | Mar 27 – May 10 |
| Spinach | Sow outdoors (fall) | Jul 18 – Aug 22 |
| Radishes | Sow outdoors (spring) | Apr 3 – May 24 |
| Radishes | Sow outdoors (fall) | Jul 1 – Sep 1 |
| Kale | Sow outdoors (spring) | Apr 20 – May 10 |
| Kale | Sow outdoors (fall) | Jun 24 – Aug 1 |
| Carrots | Sow outdoors (spring) | May 4 – Jun 19 |
| Carrots | Sow outdoors (fall) | Jun 1 – Jul 17 |
| Garlic | Plant outdoors (fall) | Oct 1 – Nov 1 |
Where these dates come from
ZIP code 49045 is matched to the NOAA station Dowagiac 1 W, MI, 15.2 km away, at 740 ft elevation (21 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Dowagiac 1 W, MI (used) | 740 ft | May 4 | Oct 11 |
| Eau Claire 4 Ne, MI | 840 ft | Apr 22 | Oct 30 |
| Bloomingdale, MI | 736 ft | May 7 | Oct 11 |
| Benton Harbor Ap, MI | 625 ft | May 5 | Oct 15 |
Frost dates near Decatur
- Lawrence, MI 49064 · last May 7, first Oct 11
- Dowagiac, MI 49047 · last May 4, first Oct 11
- Hartford, MI 49057 · last May 4, first Oct 17
- Lawton, MI 49065 · last Apr 28, first Oct 18
- Paw Paw, MI 49079 · last May 7, first Oct 11
- Marcellus, MI 49067 · last Apr 30, first Oct 17
- Watervliet, MI 49098 · last May 5, first Oct 15
- Cassopolis, MI 49031 · last May 4, first Oct 11
Frequently asked questions
- When is the last frost in Decatur, MI?
- For ZIP code 49045, the average last spring frost (32°F) is May 4, based on NOAA 1991-2020 climate normals for the Dowagiac 1 W, MI weather station. There is a 1-in-10 chance of a frost after May 22.
- When is the first frost in Decatur, MI?
- The average first fall frost (32°F) is October 11. There is a 1-in-10 chance of frost by September 27, so tender plants are at risk from that point on.
- How long is the growing season in 49045?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 158 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.