Mount Vernon, IL Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Mount Vernon, a city in Jefferson County, Illinois.
This Afternoon
79°F
Slight Chance Showers And Thunderstorms
A slight chance of showers and thunderstorms after 5pm. Partly sunny. High near 79, with temperatures falling to around 75 in the afternoon. South wind around 22 mph, with gusts as high as 30 mph. Chance of precipitation is 20%.
7-day forecast for Mount Vernon
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| This Afternoon | 79°F | Slight Chance Showers And Thunderstorms | 22 mph S | 15% |
| Tonight | 56°F | Showers And Thunderstorms | 9 to 18 mph S | 99% |
| Wednesday | 67°F | Slight Chance Rain Showers then Mostly Cloudy | 7 to 13 mph WSW | 21% |
| Wednesday Night | 43°F | Partly Cloudy | 3 mph WSW | 0% |
| Thursday | 68°F | Sunny | 3 to 10 mph WSW | 0% |
| Thursday Night | 44°F | Mostly Cloudy | 2 mph WNW | 5% |
| Friday | 61°F | Mostly Cloudy | 3 to 12 mph NNW | 2% |
| Friday Night | 39°F | Partly Cloudy | 2 to 7 mph NNW | 1% |
| Saturday | 57°F | Mostly Sunny | 2 to 6 mph NNW | 0% |
| Saturday Night | 35°F | Partly Cloudy | 1 mph NW | 1% |
| Sunday | 62°F | Sunny | 0 to 8 mph WNW | 6% |
| Sunday Night | 34°F | Mostly Clear | 3 mph NW | 4% |
| Monday | 66°F | Sunny | 1 to 9 mph W | 3% |
| Monday Night | 39°F | Mostly Clear | 5 mph SW | 0% |
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 Nov 3, 2026.