St. Clair, MI Weather & Growing Conditions
This Afternoon
67°F
Rain Showers Likely
Rain showers likely. Cloudy. High near 67, with temperatures falling to around 64 in the afternoon. East southeast wind around 7 mph. Chance of precipitation is 70%. New rainfall amounts less than a tenth of an inch possible.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| This Afternoon | 67°F | Rain Showers Likely | 7 mph ESE | 71% |
| Tonight | 56°F | Showers And Thunderstorms Likely | 3 to 7 mph ENE | 85% |
| Sunday | 68°F | Patchy Fog then Mostly Cloudy | 5 to 14 mph NNE | 61% |
| Sunday Night | 50°F | Mostly Cloudy | 7 to 14 mph NE | 0% |
| Monday | 64°F | Partly Sunny | 8 to 12 mph NE | 0% |
| Monday Night | 47°F | Mostly Cloudy | 7 to 10 mph NE | 2% |
| Tuesday | 64°F | Partly Sunny | 10 to 14 mph ENE | 9% |
| Tuesday Night | 50°F | Chance Rain Showers | 13 mph ENE | 45% |
| Wednesday | 63°F | Chance Rain Showers | 14 mph E | 45% |
| Wednesday Night | 50°F | Chance Rain Showers | 7 to 12 mph E | 39% |
| Thursday | 65°F | Chance Rain Showers | 9 mph E | 26% |
| Thursday Night | 49°F | Partly Cloudy | 3 to 7 mph ENE | 11% |
| Friday | 68°F | Mostly Sunny | 3 to 7 mph NE | 11% |
| Friday Night | 49°F | Partly Cloudy | 2 to 6 mph NNE | 5% |
Forecast source: National Weather Service (api.weather.gov). Updated through the day.
Growing snapshot for St. Clair, MI
Last spring frost
May 3
First fall frost
Oct 18
Growing season
167 days
Hardiness zone
6a
Explore more for St. Clair, MI: full frost dates · planting calendar · Michigan frost dates
Climate data from the nearest NOAA station, Algonac Wwtp, Mi (10.7 mi). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 19, 2026.