Sullivan, IL Weather & Growing Conditions
Overnight
61°F
Patchy Fog
Patchy fog. Clear, with a low around 61. Southeast wind around 2 mph.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Overnight | 61°F | Patchy Fog | 2 mph SE | 0% |
| Tuesday | 86°F | Patchy Fog then Sunny | 5 mph SSE | 0% |
| Tuesday Night | 65°F | Mostly Clear | 3 mph SSE | 0% |
| Wednesday | 86°F | Sunny | 6 mph S | 2% |
| Wednesday Night | 67°F | Slight Chance Showers And Thunderstorms | 6 mph S | 50% |
| Thursday | 83°F | Showers And Thunderstorms | 3 to 7 mph SSW | 75% |
| Thursday Night | 66°F | Chance Showers And Thunderstorms | 5 mph S | 29% |
| Friday | 84°F | Slight Chance Showers And Thunderstorms | 5 mph SSW | 18% |
| Friday Night | 66°F | Slight Chance Showers And Thunderstorms | 3 mph SSW | 18% |
| Saturday | 86°F | Slight Chance Rain Showers then Slight Chance Showers And Thunderstorms | 5 mph SSW | 18% |
| Saturday Night | 69°F | Slight Chance Showers And Thunderstorms then Mostly Clear | 6 mph SSW | 15% |
| Sunday | 88°F | Sunny | 6 to 10 mph SSW | 7% |
| Sunday Night | 71°F | Mostly Clear | 9 mph SSW | 10% |
| Monday | 89°F | Mostly Sunny | 10 mph SSW | 12% |
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 Aug 4, 2026.