Historical weather data, all-time temperature records, and monthly climate averages for Upper Alton, IL. Explore typical weather conditions by week for trip planning, and see how today compares to the historical record.
April 5th sits right in the thick of spring's unpredictability for Upper Alton — the average high of 60° feels pleasant, but this date has swung from a brutal 23° in 1987 to a shirt-sleeve 89° back in 1946. There's about a 1-in-3 chance of rain today, so keep an umbrella handy, though snow is essentially off the table.
Upper Alton doesn't mess around at the extremes — a scorching 116° in July 1946 and a bone-chilling -16° in January 1982 give this town a temperature range of 132 degrees across its recorded history. April is also when the wettest single day on record hit: 7.7 inches of rain on April 23, 1996.
Summer is the main event here, with highs in the upper 80s from late June through August and a peak around July 9–15. Winters are cold but not brutal, with January highs averaging just 38°. If you're trying to stay dry, avoid late April — the week of April 23 is the wettest of the year, averaging over an inch of precipitation.