Frost dates for 48202Detroit, 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 48202 is matched to the NOAA station Detroit City Ap, MI, 6.7 km away, at 626 ft elevation (4 ft lower 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 48206 · 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
- Hazel Park, MI 48030 · last Apr 21, first Oct 31
- Dearborn, MI 48126 · last May 1, first Oct 15
- Warren, MI 48091 · last Apr 21, first Oct 31
- Ferndale, MI 48220 · last Apr 21, first Oct 31
- Pleasant Ridge, MI 48069 · last Apr 21, first Oct 31
Frequently asked questions
- When is the last frost in Detroit, MI?
- For ZIP code 48202, 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 48202?
- 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.