Marietta, IL Weather & Growing Conditions
Today
88°F
Mostly Sunny
Mostly sunny, with a high near 88. South southwest wind 2 to 6 mph.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Today | 88°F | Mostly Sunny | 2 to 6 mph SSW | 0% |
| Tonight | 67°F | Partly Cloudy then Slight Chance Showers And Thunderstorms | 3 mph SSE | 24% |
| Wednesday | 84°F | Chance Showers And Thunderstorms | 3 mph SSW | 55% |
| Wednesday Night | 65°F | Chance Showers And Thunderstorms then Showers And Thunderstorms | 0 to 3 mph NNW | 87% |
| Thursday | 81°F | Showers And Thunderstorms | 1 mph S | 78% |
| Thursday Night | 63°F | Partly Cloudy | 0 mph | 7% |
| Friday | 83°F | Mostly Sunny | 0 mph | 5% |
| Friday Night | 65°F | Slight Chance Showers And Thunderstorms | 0 mph | 17% |
| Saturday | 86°F | Slight Chance Showers And Thunderstorms then Sunny | 2 mph SW | 15% |
| Saturday Night | 70°F | Mostly Clear | 0 to 3 mph SSW | 8% |
| Sunday | 88°F | Sunny | 5 to 9 mph SSW | 6% |
| Sunday Night | 70°F | Mostly Clear then Slight Chance Showers And Thunderstorms | 6 mph SSW | 17% |
| Monday | 88°F | Slight Chance Showers And Thunderstorms then Mostly Sunny | 7 mph SSW | 17% |
| Monday Night | 71°F | Slight Chance Showers And Thunderstorms | 6 mph SW | 29% |
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 Aug 4, 2026.