You don't have to be a weather forecaster to be a long-distance runner.

Todd Hamill is both.

Andy Sharp/AJC (ENLARGE)

Last year, runners complained of water shortages when ING Georgia Marathon officials couldn't replenish water stations fast enough.

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Hamill, a meteorologist with the Southeast River Forecast Center in Peachtree City, has easy access to long-range forecasts. It's one of the ways he keeps track of water levels of rivers all across the region. He's been eyeing the forecast for March 30 for another reason.

That's race day for the ING Georgia Marathon and Half-Marathon, and Hamill is registered for the 13.1-mile half-marathon.

"It's one of the advantages of having my job," said Hamill, who runs in marathons and half-marathons and is an Ironman triathlete. "So far, it looks like it will rain Friday and Saturday, but Sunday looks OK."

But you never know about March weather, Hamill said. Conditions can range from ice to high heat to severe storms. Last year, in the inaugural Georgia Marathon on March 25, runners and organizers were surprised by temperatures that climbed past 80 degrees by noon. Normal temps for late March in north Georgia are upper 60s for highs and upper 40s for lows.

"The next week it was 29, and we had an ice storm," race director Victoria Seahorn said.

Next Sunday's forecast calls for a high of 68, a low of 47 and sunny skies.

That would be good news for the Georgia Marathon and its 15,000 participants. Last year, runners complained of water shortages when race officials couldn't replenish water stations fast enough. That won't happen this year, Seahorn promises, with water trucks standing by at all 23 stations.

The lesson learned from the unexpected weather shows that race organizers and participants should be prepared for any eventuality. There were frost warnings in the north Georgia mountains this weekend and near freezing temps were predicted for metro Atlanta.

"You have huge variability with weather in the spring," Hamill said. "Having [the marathon] in March; there can be the good and the bad."

Weather is part of the race preparation, says Seahorn, and the roller coaster weather of March can be a challenge. Weather is part of the race's crisis plan, which has contingencies for everything from tornadoes to terrorism.

If it's cold, the race will have mylar blankets and portable heaters ready. If it's hot, plenty of water is needed, and medical workers will be ready for any problems.

Last year's hot weather resulted in "a low volume of [medical] incidents," Seahorn said. "We were so thankful of that." Ten runners were sent to the hospital, according to reports, but none was serious.

There also is an evacuation plan – with shelters planned along the route — in case of severe weather.

"It's a challenge to try to prepare for everything." said Seahorn, who has run 20 marathons. "[March weather] is kind of hit or miss, but hopefully, it will be beautiful."

It also can be a challenge for runners to be prepared, too. Most running experts say that marathoners should add 20 degrees to the actual temp to account for an increase in core body temperature, and hydration is important in any weather.

If it's hot, light fabrics will keep you cooler. Spandex shorts under your shorts can prevent chafing, according to CompleteRunning.com, which includes tips, race information and blogs for runners.

If cold, you need to stay warm before the race. Layered clothing can allow for peeling off when you warm up during the run. Stay away from cotton.

"Literally, you wait to decide what to wear on Saturday night," Seahorn said. "That's kind of the rule of thumb for all marathoners."

All bets are off if it rains, especially a cold rain. You should stay dry and warm as best you can, but "once the race starts, well, there's just not much that you can do ... You kind of suck it up and run," Hamill said. "I'd almost rather run in the snow than in a cold rain."