I've been discussing all the final details of the race plan with a runner in Los Angeles who will be running the LA Marathon this weekend. As it turns out, it's going to be warm this weekend for the race, with an expected high on race day of around 80 degrees. Many major marathons in recent years have been characterized by warmer-than-expected temperatures (though 80 isn't out of the ordinary for Southern California). Let's say your marathon or half marathon is coming up, and the forecast is for more heat than you hoped for. What should you do?