Historical weather data, all-time temperature records, and monthly climate averages for DeKalb, IL. Explore typical weather conditions by week for trip planning, and see how today compares to the historical record.
April 4th in DeKalb sits right in the middle of spring's uncertainty — expect a high near 55° and a low around 33°, but history shows this date can swing wildly. The record high of 77° in 1996 and record low of 13° in 1975 are 64 degrees apart, which tells you everything about early April here. There's a coin-flip chance of rain (52%), but snow is nearly off the table at just 2%.
DeKalb earns its Midwestern stripes with a 130-degree spread between its all-time extremes — 103° in August 1988 and a brutal -27° in January 1985. Single-day rainfall can be dramatic too, with 8.09 inches falling on July 18, 1996, and winter storms capable of dropping over a foot and a half of snow, as happened on February 2, 2011.
DeKalb's summer peak runs mid-July, with average highs of 85° and the year's heaviest rain (about 1.3 inches per week) arriving at the same time — pack accordingly. Winter is genuinely cold, with January highs averaging just 26° during the coldest stretch of the year. Spring and fall offer pleasant shoulder seasons, with April climbing to 59° and October holding at a comfortable 63°.