Frost dates for Dearborn, MI
At Dearborn, the median last spring frost (32°F) is May 1 and the median first fall frost is Oct 15, for a typical growing season of 166 days. For a 90% chance that the last frost has passed, wait until May 18. Nearby ZIP codes are in USDA hardiness zone 6b.
- May 1Last spring frost (median)50% chance of 32°F after this date
- May 18Safer planting date10% chance of 32°F after this date
- Oct 15First fall frost (median)50% chance of 32°F by this date
- 166 daysGrowing season (median)between 32°F freezes
Last spring frost dates
The chance that the temperature drops to the threshold after each date.
| Temperature | 90% chance later | 50% chance later | 10% chance later |
|---|---|---|---|
| 36°F | Apr 27 | May 12 | May 27 |
| 32°F | Apr 17 | May 1 | May 18 |
| 28°F | Apr 5 | Apr 20 | May 7 |
| 24°F | Mar 23 | Apr 6 | Apr 21 |
First fall frost dates
The chance that the temperature has dropped to the threshold by each date.
| Temperature | 10% chance by | 50% chance by | 90% chance by |
|---|---|---|---|
| 36°F | Sep 24 | Oct 5 | Oct 18 |
| 32°F | Oct 1 | Oct 15 | Oct 28 |
| 28°F | Oct 13 | Oct 28 | Nov 12 |
| 24°F | Oct 27 | Nov 10 | Nov 27 |
Growing season length
Days between the last spring and first fall freeze, as the length reached in 9, 5 and 1 out of 10 years.
| Temperature | 9 in 10 years at least | 5 in 10 years at least | 1 in 10 years at least |
|---|---|---|---|
| 36°F | 128 days | 146 days | 165 days |
| 32°F | 147 days | 166 days | 186 days |
| 28°F | 169 days | 190 days | 211 days |
| 24°F | 194 days | 215 days | 237 days |
Chance of a freeze in any year
| Temperature | Chance per year |
|---|---|
| 36°F | 100% |
| 32°F | 100% |
| 28°F | 100% |
| 24°F | 100% |
ZIP codes whose closest station is this one
| ZIP | Hardiness zone | Avg. extreme low | Distance |
|---|---|---|---|
| 48128 | 6b | -5 to 0°F | 2 km |
| 48124 | 6b | -5 to 0°F | 3 km |
| 48127 | 6b | -5 to 0°F | 4 km |
| 48125 | 6b | -5 to 0°F | 5 km |
| 48122 | 6b | -5 to 0°F | 6 km |
| 48101 | 6b | -5 to 0°F | 7 km |
| 48239 | 6b | -5 to 0°F | 7 km |
| 48135 | 6b | -5 to 0°F | 9 km |
| 48146 | 6b | -5 to 0°F | 10 km |
| 48229 | 6b | -5 to 0°F | 11 km |
| 48185 | 6b | -5 to 0°F | 12 km |
| 48192 | 6b | -5 to 0°F | 14 km |
Not the official USDA Plant Hardiness Zone Map. Zones shown here are the values published in the USDA-ARS / Oregon State University PRISM Group 2023 ZIP code tables, shown unaltered. For the official interactive map, visit planthardiness.ars.usda.gov.
About this station
- NOAA station ID USC00202015, at 42.3194, -83.2378, elevation 184 m (605 ft).
- Data quality: Standard (24+ years of data), 25 years of freeze data.
- Average days per year at or below 32°F: 136.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Dearborn #2 (6 km)
- Detroit Metro Airport (12 km)
- Farmington (19 km)
- Detroit City Airport (21 km)
- Detroit Willow Run Airport (26 km)
- Grosse Pointe Farms (30 km)
- Carleton 2w (33 km)
- Ann Arbor U Of Mich (35 km)
Sources
- NOAA National Centers for Environmental Information, U.S. Climate Normals 1991–2020, annual/seasonal normals by station (version 1.0.1), file dated June 27, 2023; documentation.
- USDA Agricultural Research Service and PRISM Group, Oregon State University, 2023 Plant Hardiness Zone Map ZIP code tables (CONUS, Alaska, Hawaii, Puerto Rico), files dated November 17, 2023. Data © PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed November 1, 2026. Official map: planthardiness.ars.usda.gov.
- U.S. Census Bureau, 2024 Gazetteer ZIP Code Tabulation Areas file, dated August 30, 2024 (ZIP centroids used to find the nearest station).
Freeze dates are 30-year probabilities, not forecasts. Check your local forecast before planting tender plants.