Sullivan, IL Weather & Growing Conditions
Overnight
58°F
Chance Light Rain
A chance of rain. Mostly cloudy, with a low around 58. South southwest wind around 13 mph, with gusts as high as 23 mph. Chance of precipitation is 40%. New rainfall amounts between a tenth and quarter of an inch possible.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Overnight | 58°F | Chance Light Rain | 13 mph SSW | 37% |
| Wednesday | 62°F | Slight Chance Light Rain then Slight Chance Drizzle | 10 to 14 mph SW | 20% |
| Wednesday Night | 43°F | Slight Chance Drizzle then Mostly Cloudy | 10 mph WSW | 10% |
| Thursday | 62°F | Partly Sunny | 9 to 14 mph WSW | 4% |
| Thursday Night | 41°F | Mostly Cloudy | 6 mph WNW | 1% |
| Friday | 54°F | Partly Sunny | 7 to 10 mph NNW | 5% |
| Friday Night | 32°F | Partly Cloudy | 3 to 8 mph NNW | 0% |
| Saturday | 54°F | Sunny | 6 mph NNW | 0% |
| Saturday Night | 31°F | Partly Cloudy | 2 mph NW | 0% |
| Sunday | 59°F | Sunny | 2 to 8 mph WNW | 1% |
| Sunday Night | 32°F | Clear | 3 mph W | 0% |
| Monday | 64°F | Sunny | 1 to 7 mph SW | 0% |
| Monday Night | 37°F | Clear | 5 mph SW | 0% |
| Tuesday | 66°F | Sunny | 6 mph W | 1% |
Forecast source: National Weather Service (api.weather.gov). Updated through the day.
Growing snapshot for Sullivan, IL
Last spring frost
Apr 15
First fall frost
Oct 22
Growing season
187 days
Hardiness zone
6a
Explore more for Sullivan, IL: full frost dates · planting calendar · Illinois frost dates
Climate data from the nearest NOAA station, Sullivan 3S, Il (2.6 mi). Frost dates are 1991–2020 averages, not a forecast. Page updated Nov 4, 2026.