Flat Rock, IL Weather & Growing Conditions
Today
96°F
Mostly Sunny then Slight Chance Showers And Thunderstorms
A slight chance of showers and thunderstorms after 1pm. Mostly sunny, with a high near 96. Heat index values as high as 100. Southwest wind 5 to 8 mph. Chance of precipitation is 20%.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Today | 96°F | Mostly Sunny then Slight Chance Showers And Thunderstorms | 5 to 8 mph SW | 21% |
| Tonight | 72°F | Partly Cloudy | 6 mph SSE | 10% |
| Sunday | 94°F | Mostly Sunny then Slight Chance Showers And Thunderstorms | 5 to 9 mph WNW | 15% |
| Sunday Night | 65°F | Chance Showers And Thunderstorms | 10 mph NNE | 48% |
| Monday | 79°F | Showers And Thunderstorms Likely | 9 to 13 mph NE | 62% |
| Monday Night | 58°F | Showers And Thunderstorms Likely then Slight Chance Showers And Thunderstorms | 9 to 13 mph NE | 62% |
| Tuesday | 73°F | Chance Showers And Thunderstorms | 13 mph NNE | 32% |
| Tuesday Night | 56°F | Slight Chance Showers And Thunderstorms then Mostly Cloudy | 7 to 13 mph NNE | 21% |
| Wednesday | 74°F | Partly Sunny | 7 to 10 mph N | 5% |
| Wednesday Night | 56°F | Partly Cloudy | 5 to 10 mph N | 4% |
| Thursday | 75°F | Mostly Sunny | 6 to 10 mph N | 4% |
| Thursday Night | 57°F | Partly Cloudy | 5 to 9 mph NNE | 4% |
| Friday | 77°F | Mostly Sunny | 6 to 10 mph NNE | 3% |
| Friday Night | 55°F | Partly Cloudy | 5 to 9 mph NE | 1% |
Forecast source: National Weather Service (api.weather.gov). Updated through the day.
Growing snapshot for Flat Rock, IL
Last spring frost
Apr 8
First fall frost
Oct 26
Growing season
200 days
Hardiness zone
6b
Explore more for Flat Rock, IL: full frost dates · planting calendar · Illinois frost dates
Climate data from the nearest NOAA station, Lawrenceville Intl Ap, Il (7.9 mi). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 19, 2026.