Frost dates for 48209Detroit, MI
The average last spring frost in Detroit is May 1 and the average first fall frost is October 15, giving a typical growing season of about 166 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 1
- Average first fall frost
- Oct 15
- Growing season
- 166 days
Safer after May 18 (1-in-10 risk)
Possible by Oct 1 (1-in-10 risk)
Last frost typically in 196 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 27 · May 12 · May 27 | Sep 24 · Oct 5 · Oct 18 | 146 days | 100% |
| Frost / freeze (32°F) | Apr 17 · May 1 · May 18 | Oct 1 · Oct 15 · Oct 28 | 166 days | 100% |
| Hard freeze (28°F) | Apr 5 · Apr 20 · May 7 | Oct 13 · Oct 28 · Nov 12 | 190 days | 100% |
Planting calendar for Detroit
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 31 – Jun 6 |
| Tomatoes | Transplant outdoors | May 17 – Jun 25 |
| Peppers | Start seeds indoors | Mar 31 – May 1 |
| Peppers | Transplant outdoors | May 31 – Jul 1 |
| Eggplant | Start seeds indoors | Apr 17 – May 16 |
| Eggplant | Transplant outdoors | May 31 – Jul 1 |
| Cucumbers | Sow outdoors | May 31 – Jul 5 |
| Summer squash | Sow outdoors | May 17 – Jul 1 |
| Winter squash & pumpkins | Sow outdoors | May 31 – Jul 1 |
| Snap beans | Sow outdoors | May 17 – Jul 28 |
| Sweet corn | Sow outdoors | May 17 – Jun 25 |
| Watermelon & cantaloupe | Sow outdoors | May 31 – Jul 1 |
| Okra | Sow outdoors | May 24 – Jun 16 |
| Peas | Sow outdoors (spring) | Mar 31 – May 16 |
| Potatoes | Plant outdoors (spring) | Mar 31 – May 31 |
| Onions | Start seeds indoors (spring) | Feb 17 – Mar 16 |
| Onions | Transplant outdoors (spring) | Apr 17 – May 16 |
| Broccoli | Start seeds indoors (spring) | Mar 13 – Apr 16 |
| Broccoli | Transplant outdoors (spring) | Apr 17 – May 16 |
| Broccoli | Start seeds indoors (fall) | Jun 15 – Jun 25 |
| Broccoli | Transplant outdoors (fall) | Jul 15 – Jul 26 |
| Cabbage | Start seeds indoors (spring) | Mar 3 – Mar 31 |
| Cabbage | Transplant outdoors (spring) | Mar 31 – May 1 |
| Cabbage | Start seeds indoors (fall) | Jun 5 – Jul 5 |
| Cabbage | Transplant outdoors (fall) | Jul 5 – Aug 5 |
| Leaf lettuce | Sow outdoors (spring) | Mar 31 – Jun 16 |
| Leaf lettuce | Sow outdoors (fall) | Jul 5 – Aug 21 |
| Spinach | Sow outdoors (spring) | Mar 24 – May 7 |
| Spinach | Sow outdoors (fall) | Jul 22 – Aug 26 |
| Radishes | Sow outdoors (spring) | Mar 31 – May 21 |
| Radishes | Sow outdoors (fall) | Jul 5 – Sep 5 |
| Kale | Sow outdoors (spring) | Apr 17 – May 7 |
| Kale | Sow outdoors (fall) | Jun 28 – Aug 5 |
| Carrots | Sow outdoors (spring) | May 1 – Jun 16 |
| Carrots | Sow outdoors (fall) | Jun 5 – Jul 21 |
| Garlic | Plant outdoors (fall) | Oct 5 – Nov 5 |
Where these dates come from
ZIP code 48209 is matched to the NOAA station Dearborn, MI, 10.1 km away, at 605 ft elevation (14 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Dearborn, MI (used) | 605 ft | May 1 | Oct 15 |
| Dearborn #2, MI | 605 ft | Apr 27 | Oct 25 |
| Detroit City Ap, MI | 626 ft | Apr 21 | Oct 31 |
| Detroit Metro Ap, MI | 631 ft | Apr 20 | Oct 27 |
Frost dates near Detroit
- Detroit, MI 48210 · last May 1, first Oct 15
- River Rouge, MI 48218 · last May 1, first Oct 15
- Dearborn, MI 48120 · last May 1, first Oct 15
- Melvindale, MI 48122 · last May 1, first Oct 15
- Ecorse, MI 48229 · last May 1, first Oct 15
- Garden City, MI 48136 · last May 1, first Oct 15
- Lincoln Park, MI 48146 · last May 1, first Oct 15
- Allen Park, MI 48101 · last May 1, first Oct 15
Frequently asked questions
- When is the last frost in Detroit, MI?
- For ZIP code 48209, the average last spring frost (32°F) is May 1, based on NOAA 1991-2020 climate normals for the Dearborn, MI weather station. There is a 1-in-10 chance of a frost after May 18.
- When is the first frost in Detroit, MI?
- The average first fall frost (32°F) is October 15. There is a 1-in-10 chance of frost by October 1, so tender plants are at risk from that point on.
- How long is the growing season in 48209?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 166 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.