Sonic boom heard and felt in Western Fond du Lac County

Hundreds of people in western Fond du Lac County were stunned by a large boom that shook their houses Monday, December 8, 2025, just before 7 p.m.

While not confirmed, it is thought the sound came from a sonic boom set off by military jets doing training in the area.

According to a press release, Wisconsin Air National Guard’s 115th Fighter Wing in Madison said that F 35 fighter jets would be doing nighttime training exercises this week Monday through Thursday.

Reports came in from Ripon down to Waupun reporting the sound, which some said rattled windows and dishes in their homes.

Sonic booms occur when the jets fly faster than the speed of sound, and the soundwaves emitted from the jet, build up just behind it. When this wave of built up sound reaches the ground, it creates the boom sound. While the US has banned civil aircraft from creating sonic booms in 1973, military jets are exempt from this ban for the purpose of operations and training.

The National Guard says training this week will go until about 8 p.m. each night.