Mount Vernon, IL Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Mount Vernon, a city in Jefferson County, Illinois.
Overnight
71°F
Mostly Clear
Mostly clear. Low around 71, with temperatures rising to around 73 overnight. South southeast wind around 1 mph.
7-day forecast for Mount Vernon
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Overnight | 71°F | Mostly Clear | 1 mph SSE | 2% |
| Saturday | 99°F | Sunny | 1 to 7 mph SW | 5% |
| Saturday Night | 72°F | Partly Cloudy | 3 mph SSW | 2% |
| Sunday | 96°F | Mostly Sunny | 2 to 6 mph W | 1% |
| Sunday Night | 67°F | Mostly Cloudy then Chance Showers And Thunderstorms | 7 mph NNE | 47% |
| Monday | 83°F | Showers And Thunderstorms Likely | 5 to 12 mph NE | 63% |
| Monday Night | 59°F | Showers And Thunderstorms Likely then Slight Chance Showers And Thunderstorms | 5 to 12 mph NNE | 63% |
| Tuesday | 75°F | Chance Showers And Thunderstorms | 7 to 13 mph NNE | 34% |
| Tuesday Night | 54°F | Slight Chance Rain Showers then Partly Cloudy | 5 to 13 mph N | 15% |
| Wednesday | 76°F | Mostly Sunny | 5 to 10 mph N | 3% |
| Wednesday Night | 55°F | Partly Cloudy | 2 to 10 mph N | 1% |
| Thursday | 77°F | Mostly Sunny | 2 to 9 mph N | 2% |
| Thursday Night | 56°F | Partly Cloudy | 1 to 8 mph NNE | 3% |
| Friday | 79°F | Mostly Sunny | 2 to 9 mph NNE | 3% |
Forecast source: National Weather Service (api.weather.gov) for Mount Vernon (38.314, -88.917). Updated through the day.
Growing snapshot for Mount Vernon
Last spring frost
Apr 11
First fall frost
Oct 22
Growing season
193 days
Hardiness zone
6b
More local growing data for Mount Vernon: nearby ZIP 62864 weather · frost dates · planting calendar · Illinois frost dates
Nearby towns & communities
Climate data from the nearest NOAA station, Mt Vernon 3 Ne, Il (2.9 mi from Mount Vernon). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 19, 2026.