USA Women's Half Marathon Islamorada

Entry runs through a lottery that opens months ahead, which keeps the field capped and the Overseas Highway logistics workable. The race is built as a destination weekend rather than a local road race, and the single half marathon distance means the whole morning belongs to one start. Runners who want a fast Keys half in winter tend to plan travel around it well in advance.

An out and back on Keys road with almost no elevation to speak of, starting and finishing at Robbie's of Islamorada. Flat does not automatically mean fast here, because there is little shade and the return leg can turn into a headwind. The 4.5 hour cutoff leaves room for walkers.

Early February in the Keys is the mildest part of the year, but a 7am start still often means humidity in the 80 percent range and temperatures climbing through the race. Sun exposure on the open highway is the main stressor once the field spreads out.