WORCESTER, Mass. - The weather for the Boston Marathon is about 10 degrees cooler and a bit cloudier than originally expected.

Dr. Stacy Potts says the change will favor the runners. The UMass Memorial Health family doctor is back along the course this year, helping out in one of the medical tents. She said the trickiest thing about the Boston Marathon is the time of year in which it happens, because most runners train in much colder weather.

“Heat on race day is particularly hard for Boston runners because of the change, especially for runners who take longer on the course. They're going to be out there in the heavier sun and hotter weather, as well as just being out there longer,” Potts said. “So it’s hard to stay hydrated. It’s hard to keep your balances quite right in the chemistry of our bodies in terms of electrolytes and so there's a lot of challenges in the day. “

Potts has run nearly 60 marathons herself, one in each of the 50 states. While she's never run Boston, she said her experience running marathons helps her better treat runners along the course. 

“A lot of runners stop in with muscle cramps particularly calf and hamstring cramps and we have ways of helping them with that,” she said. “A lot of the times it's very simple things like blisters and muscle cramps.”

You can find Potts in the tent at mile 19.9 in Newton.