I definitely had to "dress the part" as the temps were just above freezing at dusk, but the cool wind in the lungs felt awesome.
There's a reason that most marathons are in the fall--you have roughly 18 weeks of good warm weather in which to train which leads up to cool mornings. On race day, a cool morning keeps the body engine temperature cooler and there seems to be a boost when puffing in cool morning weather. That is unless you're running the Chicago Marathon. I can only surmise that the late Chicago starts are due to TV broadcasting schedules, the last two years have been brutally hot in part due to the late start. At last year's Chicago Marathon, I did my customary two mile jog the day before around the finish line area around 9AM and it was HOT! I knew I was in for a hot race the next day.
Other than Chicago, cool temps are a runner's best friend (I'll skip the rain and wind.)
While today felt like a postcard, tomorrow's postcard may look more like Buffalo, NY. Forecast calls for Snain--combination of snow and rain for my 22 mile run.