The Houston Marathon Committee announced Friday that the race will begin under a yellow caution flag, which indicates a moderate level of risk. Temperatures are expected to reach 73 degrees by noon, and humidity will exceed 90 percent.
This year's start may well rank among the warmest starts in the race's history.
Marathon organizers recommend that runners stay hydrated, choose breathable fabrics that wick sweat, wear a hat and adjust pace goals.
"Slow down, slow down, slow down," Dr. John Cianca, medical director of the Houston Marathon Committee, said in an email to runners.
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"It's going to be hot and humid -- not ideal weather -- so run responsibly and adjust your pace to reduce the risk of overheating. This is not the year to set a personal best. It will be more difficult than you anticipated, so make adjustments," he added.
Runners who experience headache, fatigue, profuse sweating, nausea, clammy skin, labored breathing, mental confusion or gastro-intestinal issues should seek medical care immediately.
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