I'm also down in the heat of Miami and even though I've been known to do crazy things like running around a local park in the middle of August,in the middle of the day with 95 degrees with heat indexes of 120 just to see how many laps (7/8th of a mile) I can do,I know when I'm done,I'm done,5-7 laps or whatever but I don't have to go any further.For a full marathon however I want to see no temperatures even close to 80,even a high of 75 is too much.26 miles is a long way and the higher temps just bring out the issues faster,dehydration and cramping,chafing,etc..Everything about 2014 was so more pleasant than 2013 with the highs in the low to mid 80's.Obviously I'll deal with the heat better than someone from up north but even so I remember getting some pretty nasty chafing in 2013 that I didn't get in 2014.