Frost dates for Port Austin Wastewater Plant, MI
At Port Austin Wastewater Plant, the median last spring frost (32°F) is May 4 and the median first fall frost is Oct 26, for a typical growing season of 172 days. For a 90% chance that the last frost has passed, wait until May 19. Nearby ZIP codes are in USDA hardiness zone 6a.
- May 4Last spring frost (median)50% chance of 32°F after this date
- May 19Safer planting date10% chance of 32°F after this date
- Oct 26First fall frost (median)50% chance of 32°F by this date
- 172 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 | May 1 | May 16 | May 31 |
| 32°F | Apr 20 | May 4 | May 19 |
| 28°F | Apr 8 | Apr 21 | May 5 |
| 24°F | Mar 27 | Apr 9 | Apr 23 |
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 26 | Oct 9 | Oct 26 |
| 32°F | Oct 7 | Oct 26 | Nov 8 |
| 28°F | Oct 25 | Nov 7 | Nov 21 |
| 24°F | Nov 3 | Nov 19 | Dec 3 |
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 | 125 days | 145 days | 167 days |
| 32°F | 150 days | 172 days | 191 days |
| 28°F | 178 days | 197 days | 218 days |
| 24°F | 202 days | 222 days | 244 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 |
|---|---|---|---|
| 48467 | 6a | -10 to -5°F | 4 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 USC00206662, at 44.0469, -82.9703, elevation 184 m (605 ft).
- Data quality: Representative (10+ years), 10 years of freeze data.
- Average days per year at or below 32°F: 145.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Port Hope (14 km)
- Filion 5nnw (17 km)
- Port Hope (23 km)
- Bad Axe (27 km)
- Harbor Beach 1 SSE (35 km)
- E Tawas (50 km)
- Cass City 1 SSW (54 km)
- Sandusky (71 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.