Historical weather data, all-time temperature records, and monthly climate averages for Mount Vernon, IL. Explore typical weather conditions by week for trip planning, and see how today compares to the historical record.
April 5 in Mount Vernon sits right in the middle of spring's warm-up, with average highs of 62° and lows of 40° across 129 years of records. The date has seen some wild swings though — an 85° scorcher in 1954 and a brutal 22° low back in 1944. There's about a 1-in-3 chance of rain today, but snow is nearly off the table.
Mount Vernon's weather history is not for the faint of heart — the thermometer has swung from a bone-cracking -22° in February 1899 all the way up to a stifling 114° in July 1936, a range of 136 degrees. A single August day in 1946 dropped 6.17 inches of rain, and a February storm in 1912 buried the area under 14 inches of snow.
Summers here are legitimately hot — the warmest week of the year averages a high of 90°, and June through August all push into the mid-to-upper 80s. If you're cold-averse, January and February are the ones to avoid, with highs only reaching the low 40s. Plan for rain in late April through early May, the wettest stretch of the year.