At least 26 tornadoes formed during the storm on Dec. 1.
WATCH: Tornado reported in LItchfield, Illinois
NWS staff planned to perform another severe storm survey on Dec. 4, so the total could increase. But 26 tornadoes beats the previous record of 21 tornadoes, which was on Dec. 18-19 in 1957.
The Dec. 1 tornado outbreak also ranks as the third largest in Illinois during any month of the years, the weather service said. The biggest outbreak, with 39 tornadoes, occurred on April 19, 1996. The second-largest outbreak, with 36 tornadoes, occurred on April 2, 2006.
One of the twisters that hit Taylorville, Illinois, on Dec. 1 was an EF-3.
WATCH: Raw video shows devastation near Taylorville, Illinois
On the same day, four friends duck hunting in Havana, Illinois, witnessed a tornado form while they were out on the water. They said it's something they'll never forget.
"Never ever seen a tornado come down, form and actually destroy something. Just to witness the whole entire process was crazy," said Levi Sarff, one of the duck hunters.
While this was an opportunity for a spectacular photo, the group said they won't get that close to a twister again.
Illinois tornado outbreak: Cleanup continues Monday after at least 20 touchdowns reported