Marietta, IL Weather & Growing Conditions
Tonight
52°F
Light Rain Likely then Slight Chance Rain Showers
Rain likely and a slight chance of thunderstorms before midnight, then a slight chance of rain showers between midnight and 3am. Mostly cloudy, with a low around 52. South southwest wind 10 to 16 mph, with gusts as high as 26 mph. Chance of precipitation is 70%. New rainfall amounts between a tenth and quarter of an inch possible.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Tonight | 52°F | Light Rain Likely then Slight Chance Rain Showers | 10 to 16 mph SSW | 69% |
| Wednesday | 57°F | Chance Rain Showers then Mostly Cloudy | 13 to 16 mph SW | 14% |
| Wednesday Night | 44°F | Mostly Cloudy | 10 mph SW | 4% |
| Thursday | 57°F | Partly Sunny | 7 to 13 mph W | 13% |
| Thursday Night | 42°F | Mostly Cloudy then Chance Light Rain | 3 to 7 mph NW | 29% |
| Friday | 54°F | Mostly Cloudy | 6 to 9 mph N | 13% |
| Friday Night | 35°F | Mostly Cloudy | 0 to 5 mph N | 1% |
| Saturday | 53°F | Mostly Sunny | 2 mph WNW | 2% |
| Saturday Night | 34°F | Mostly Clear | 2 mph WNW | 1% |
| Sunday | 59°F | Sunny | 2 to 7 mph WNW | 10% |
| Sunday Night | 35°F | Mostly Clear | 3 mph W | 3% |
| Monday | 64°F | Sunny | 2 to 9 mph SW | 1% |
| Monday Night | 40°F | Mostly Clear | 5 mph WSW | 0% |
| Tuesday | 66°F | Sunny | 5 mph NW | 0% |
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 Nov 4, 2026.