Elizabeth Corkum, from New York City, poses for a photograph in front of a sign prior to the start of the 116th running of the Boston Marathon, in Hopkinton, Mass., Monday, April 16, 2012. Corkum has run five previous marathons, but this will be her first Boston Marathon. (AP Photo/Stew Milne)
(CBS/AP) BOSTON - Runners are gathering in Hopkinton for the start of the Boston Marathon with more to worry about than the up-and-down, 26.2-mile road to Copley Square.
Temperatures expected to rise into the 80s are forecast. That can be dangerous for those who aren't accustomed to running in heat.
Race organizers have warned inexperienced marathoners to sit this one out. They've been offered a deferment into next year's race.
CBS Boston: Complete marathon coverageThere's no way of knowing until after the entire field crosses the starting line how many of the 27,000 registered runners will take them up on it.
CBS Boston reports that while the temperatures will be an issue, today's heat won't to compare to the hottest marathons of all time. In 1905 and 1976, the temperature scorched to 100. Even in 1909, the temperature reached 97 - that race was called the "Inferno."
Geoffrey Mutai rode perfect temperatures last year to an unprecedented 2 hour, 3 minutes, 2 second victory that was the fastest marathon ever run. He's back to defend his title, along with fellow Kenyan Carolina Kilel on the women's side.
