Frost dates for Howell Wastewater Plant, MI
At Howell Wastewater Plant, the median last spring frost (32°F) is May 4 and the median first fall frost is Oct 7, for a typical growing season of 156 days. For a 90% chance that the last frost has passed, wait until May 21. Nearby ZIP codes are in USDA hardiness zone 6a.
- May 4Last spring frost (median)50% chance of 32°F after this date
- May 21Safer planting date10% chance of 32°F after this date
- Oct 7First fall frost (median)50% chance of 32°F by this date
- 156 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 30 | May 16 | May 31 |
| 32°F | Apr 20 | May 4 | May 21 |
| 28°F | Apr 11 | Apr 24 | May 11 |
| 24°F | Mar 31 | Apr 13 | Apr 28 |
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 17 | Sep 29 | Oct 10 |
| 32°F | Sep 27 | Oct 7 | Oct 21 |
| 28°F | Oct 5 | Oct 20 | Nov 3 |
| 24°F | Oct 18 | Nov 1 | Nov 16 |
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 | 116 days | 136 days | 155 days |
| 32°F | 136 days | 156 days | 174 days |
| 28°F | 157 days | 178 days | 196 days |
| 24°F | 182 days | 201 days | 221 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 |
|---|---|---|---|
| 48843 | 6a | -10 to -5°F | 2 km |
| 48855 | 6a | -10 to -5°F | 10 km |
| 48836 | 6a | -10 to -5°F | 14 km |
| 48892 | 6a | -10 to -5°F | 20 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 USC00203947, at 42.5939, -83.9325, elevation 280 m (917 ft).
- Data quality: Representative (10+ years), 11 years of freeze data.
- Average days per year at or below 32°F: 154.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Hell (18 km)
- Milford Gm Proving Ground (20 km)
- Whitmore Lake 1nw (21 km)
- Linden Wastewater Plant (27 km)
- Chelsea (30 km)
- Durand Wastewater Plant (37 km)
- White Lake 4e (39 km)
- Ann Arbor U Of Mich (40 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.