Cool temperatures set in, the kind that provoke record times, and that's exactly what happened for the elite and many others.
It was a record-breaking day for this year's men's winner Kenyan Sammy Wanjiru. The 22-year-old 2008 Olympic gold medalist finished in 2 hours, 5 minutes, and 41 seconds, beating both the course and American records by seconds but missing the world record of 2 hours, 3 minutes and 59 seconds set back in Berlin last year.
"My first time to Chicago, and my first time to win here. Now, I feel comfortable being the winner," Wanjiru said.
Running only her second marathon, Russian Liliya Shobukhova captured the women's division with a time of 2 hours, 25 minutes and 56 seconds.
It remained an emotional day for women's runner-up German Irina Mikitenko, who dedicated her run to her father who died recently.
"I'm a little disappointed, but I knew that my preparations were not good because of what happened. And because of that, I'm just thankful I got in second," Mikitenko said.
Close to 45,000 people from all 50 states and around the world braved the sometimes sub-freezing temperatures to participate in the 32nd running of the marathon, which wound through several of Chicago's neighborhoods.
"I was so happy that it was cooler. I'd much rather have this kind of weather than 88 [degrees]," said Tera Moody, who finished 9th among female runners.
Sunday's marathon was quite a contrast from two years ago when one participant with a heart disorder died and hundreds more collapsed because of the skyrocketing heat that eventually forced the race to be stopped. Last year, temperatures hit the 80s.
"We track weather race week. As we see the forecast, we make adjustments with our medical staff and support staff," Chicago Marathon Executive Director Carey Pinkowski said.
While some of the elite runners competed for a piece of the nearly $500,000 in prize money, most were like Angie Stuver of South Bend, Ind., who was focused on achieving her personal best.
"I wanted to run one before I was 30. I ran cross country in high school. And so, I did Chicago before I turned 30, and once you run one, you want to run a couple more," she said.
For more information on the Chicago Marathon, visit chicagomarathon.com.