The flattest marathons in our catalog are all in Florida. Surfside Beach climbs about 1 ft per mile — functionally a track. So why do first-timers keep arriving at these races and running 20 minutes slower than their training predicted? Because they shopped for elevation profile and ignored the air.
The numbers: a typical race morning at A1A scores 125 on the temp+dew scale — a 2% pace penalty, about 5 minutes for a 4:00 marathoner. Surfside Beach sits at 103 (0.5%); Life Time Miami sits at 130 (2%). None of Florida's flatness buys that back.
Now the comparison that matters. Chevron Houston Marathon climbs 6 ft/mi — real rollers, worth maybe 4 minutes over the full distance by the standard coaching rule of thumb. Its typical race morning scores 86: a 0% heat penalty. The "hilly" race is minutes faster than the "flat" one before anyone takes a step.
The ruling: when you pick a goal race, sort by climate first and terrain second. A course profile is a fixed, known quantity you can train for on any bridge or parking garage. The dew point is a tax you cannot train away — heat adaptation blunts it, it never erases it.
Florida races still have a job: they're superb winter tune-ups, and if you live here, the halves are your speed benchmarks. Just don't confuse the flattest race with the fastest one.