Marietta, IL Weather & Growing Conditions
Tonight
70°F
Partly Cloudy then Patchy Fog
Patchy fog and a slight chance of showers and thunderstorms after 5am. Partly cloudy, with a low around 70. Southeast wind around 7 mph, with gusts as high as 18 mph. Chance of precipitation is 20%.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Tonight | 70°F | Partly Cloudy then Patchy Fog | 7 mph SE | 20% |
| Saturday | 87°F | Patchy Fog then Mostly Cloudy | 5 to 8 mph SSW | 18% |
| Saturday Night | 67°F | Mostly Cloudy then Chance Showers And Thunderstorms | 3 to 7 mph N | 61% |
| Sunday | 77°F | Rain Showers Likely | 1 to 10 mph NNE | 65% |
| Sunday Night | 59°F | Showers And Thunderstorms Likely | 7 to 12 mph NE | 68% |
| Monday | 66°F | Showers And Thunderstorms Likely | 12 mph NE | 68% |
| Monday Night | 54°F | Chance Rain Showers | 7 to 12 mph NE | 49% |
| Tuesday | 64°F | Chance Rain Showers | 10 mph NE | 29% |
| Tuesday Night | 49°F | Mostly Cloudy | 3 to 7 mph NNE | 4% |
| Wednesday | 68°F | Mostly Sunny | 6 mph NNE | 2% |
| Wednesday Night | 52°F | Partly Cloudy | 0 to 3 mph NNE | 1% |
| Thursday | 69°F | Mostly Sunny | 3 mph NNE | 4% |
| Thursday Night | 54°F | Partly Cloudy | 2 mph NE | 4% |
| Friday | 71°F | Mostly Sunny | 3 mph NE | 4% |
Forecast source: National Weather Service (api.weather.gov). Updated through the day.
Growing snapshot for Marietta, IL
Last spring frost
Apr 17
First fall frost
Oct 22
Growing season
185 days
Hardiness zone
6a
Explore more for Marietta, IL: full frost dates · planting calendar · Illinois frost dates
Climate data from the nearest NOAA station, Prairie City 2S, Il (6.1 mi). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 19, 2026.