Bryan McDonald, 43, who spent 2 1/2 half hours Monday among the 19-foot waves, said conditions were ideal for winter surfing, the Chicago Sun-Times reported Tuesday.
"Sunday's snow storm brought wind, the wind stirs up the lake, and we have waves," McDonald said. "Winter gives you the best waves."
Ryan Gerard, a local surf shop owner, said strides in wetsuit technology help prevent winter wave-riders from getting hypothermia.
The surfers said their winter antics often attract the attention of emergency responders.
"We've got to go check it out and get close enough to eyeball them and see they're OK," said Chicago Fire Department spokesman Larry Langford. "Lots of times they'll give a thumbs up and we'll leave them be. They're a hardy bunch I guess."