St. Clair, MI Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for St. Clair, a city in St. Clair County, Michigan.
Tonight
54°F
Slight Chance Light Rain
A slight chance of rain. Mostly cloudy. Low around 54, with temperatures rising to around 56 overnight. Northeast wind 3 to 8 mph. Chance of precipitation is 20%. New rainfall amounts less than a tenth of an inch possible.
7-day forecast for St. Clair
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Tonight | 54°F | Slight Chance Light Rain | 3 to 8 mph NE | 22% |
| Saturday | 68°F | Chance Light Rain then Showers And Thunderstorms Likely | 3 to 7 mph ESE | 63% |
| Saturday Night | 55°F | Slight Chance Showers And Thunderstorms then Showers And Thunderstorms Likely | 3 to 7 mph E | 73% |
| Sunday | 66°F | Chance Rain Showers | 5 to 13 mph NNE | 41% |
| Sunday Night | 51°F | Slight Chance Rain Showers then Mostly Cloudy | 7 to 13 mph NE | 22% |
| Monday | 65°F | Mostly Cloudy | 8 to 12 mph NE | 5% |
| Monday Night | 48°F | Mostly Cloudy | 10 mph NE | 10% |
| Tuesday | 64°F | Mostly Cloudy then Slight Chance Rain Showers | 13 mph NE | 18% |
| Tuesday Night | 50°F | Chance Rain Showers | 12 mph ENE | 47% |
| Wednesday | 63°F | Chance Rain Showers | 12 mph ENE | 51% |
| Wednesday Night | 51°F | Chance Showers And Thunderstorms | 5 to 9 mph ENE | 51% |
| Thursday | 66°F | Slight Chance Showers And Thunderstorms | 8 mph NE | 22% |
| Thursday Night | 51°F | Slight Chance Rain Showers then Mostly Cloudy | 3 to 7 mph NE | 15% |
| Friday | 68°F | Mostly Sunny | 3 to 8 mph NNE | 10% |
Forecast source: National Weather Service (api.weather.gov) for St. Clair (42.827, -82.492). Updated through the day.
Growing snapshot for St. Clair
Last spring frost
Apr 19
First fall frost
Nov 3
Growing season
196 days
Hardiness zone
6a
More local growing data for St. Clair: nearby ZIP 48079 weather · frost dates · planting calendar · Michigan frost dates
Nearby towns & communities
Climate data from the nearest NOAA station, Port Huron, Mi (10.3 mi from St. Clair). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 19, 2026.