Frost dates for 48201Detroit, MI
The average last spring frost in Detroit is April 21 and the average first fall frost is October 31, giving a typical growing season of about 190 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Apr 21
- Average first fall frost
- Oct 31
- Growing season
- 190 days
Safer after May 6 (1-in-10 risk)
Possible by Oct 17 (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 19 · May 1 · May 18 | Oct 2 · Oct 18 · Oct 31 | 167 days | 100% |
| Frost / freeze (32°F) | Apr 7 · Apr 21 · May 6 | Oct 17 · Oct 31 · Nov 11 | 190 days | 100% |
| Hard freeze (28°F) | Mar 27 · Apr 8 · Apr 22 | Oct 29 · Nov 9 · Nov 23 | 214 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 21 – May 27 |
| Tomatoes | Transplant outdoors | May 7 – Jul 11 |
| Peppers | Start seeds indoors | Mar 21 – Apr 21 |
| Peppers | Transplant outdoors | May 21 – Jun 21 |
| Eggplant | Start seeds indoors | Apr 7 – May 6 |
| Eggplant | Transplant outdoors | May 21 – Jun 21 |
| Cucumbers | Sow outdoors | May 21 – Jul 21 |
| Summer squash | Sow outdoors | May 7 – Jun 21 |
| Winter squash & pumpkins | Sow outdoors | May 21 – Jun 21 |
| Snap beans | Sow outdoors | May 7 – Aug 13 |
| Sweet corn | Sow outdoors | May 7 – Jul 11 |
| Watermelon & cantaloupe | Sow outdoors | May 21 – Jun 21 |
| Okra | Sow outdoors | May 14 – Jun 6 |
| Peas | Sow outdoors (spring) | Mar 21 – May 6 |
| Potatoes | Plant outdoors (spring) | Mar 21 – May 21 |
| Onions | Start seeds indoors (spring) | Feb 7 – Mar 6 |
| Onions | Transplant outdoors (spring) | Apr 7 – May 6 |
| Broccoli | Start seeds indoors (spring) | Mar 3 – Apr 6 |
| Broccoli | Transplant outdoors (spring) | Apr 7 – May 6 |
| Broccoli | Start seeds indoors (fall) | Jul 1 – Jul 11 |
| Broccoli | Transplant outdoors (fall) | Jul 31 – Aug 11 |
| Cabbage | Start seeds indoors (spring) | Feb 21 – Mar 21 |
| Cabbage | Transplant outdoors (spring) | Mar 21 – Apr 21 |
| Cabbage | Start seeds indoors (fall) | Jun 21 – Jul 21 |
| Cabbage | Transplant outdoors (fall) | Jul 21 – Aug 21 |
| Leaf lettuce | Sow outdoors (spring) | Mar 21 – Jun 6 |
| Leaf lettuce | Sow outdoors (fall) | Jul 21 – Sep 6 |
| Spinach | Sow outdoors (spring) | Mar 14 – Apr 27 |
| Spinach | Sow outdoors (fall) | Aug 7 – Sep 11 |
| Radishes | Sow outdoors (spring) | Mar 21 – May 11 |
| Radishes | Sow outdoors (fall) | Jul 21 – Sep 21 |
| Kale | Sow outdoors (spring) | Apr 7 – Apr 27 |
| Kale | Sow outdoors (fall) | Jul 14 – Aug 21 |
| Carrots | Sow outdoors (spring) | Apr 21 – Jun 6 |
| Carrots | Sow outdoors (fall) | Jun 21 – Aug 6 |
| Garlic | Plant outdoors (fall) | Oct 21 – Nov 21 |
Where these dates come from
ZIP code 48201 is matched to the NOAA station Detroit City Ap, MI, 8 km away, at 626 ft elevation (6 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Detroit City Ap, MI (used) | 626 ft | Apr 21 | Oct 31 |
| Dearborn #2, MI | 605 ft | Apr 27 | Oct 25 |
| Dearborn, MI | 605 ft | May 1 | Oct 15 |
| Grosse Pointe Farms, MI | 613 ft | Apr 29 | Oct 22 |
Frost dates near Detroit
- Detroit, MI 48226 · last Apr 21, first Oct 31
- Hamtramck, MI 48212 · last Apr 21, first Oct 31
- Highland Park, MI 48203 · last Apr 21, first Oct 31
- Dearborn, MI 48120 · last May 1, first Oct 15
- River Rouge, MI 48218 · last May 1, first Oct 15
- Grosse Pointe, MI 48230 · last Apr 29, first Oct 22
- Melvindale, MI 48122 · last May 1, first Oct 15
- Ecorse, MI 48229 · last May 1, first Oct 15
Frequently asked questions
- When is the last frost in Detroit, MI?
- For ZIP code 48201, the average last spring frost (32°F) is April 21, based on NOAA 1991-2020 climate normals for the Detroit City Ap, MI weather station. There is a 1-in-10 chance of a frost after May 6.
- When is the first frost in Detroit, MI?
- The average first fall frost (32°F) is October 31. There is a 1-in-10 chance of frost by October 17, so tender plants are at risk from that point on.
- How long is the growing season in 48201?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 190 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.