In Maine, a stretch of hot weather coincides with the start of high school sports season, with many teams starting to practice two times a day.
"I'm a little bit fatigued already from the heat, and all I did was pump up soccer balls," said South Portland boys soccer coach Bryan Hoy. The team held their first practice at 9 a.m. Monday. When they started drills, it was already 80 degrees.
"We probably should have been practicing earlier this morning," said Hoy. "It would be impossible to go to noon."
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Many teams make sure the players are off the field between noon and 4 p.m., the hottest part of the day.
"Just have a lot of water available," said Dr. Krys Bigosinski, who specializes in Sports Medicine at Maine Medical Center.
Dr. Bigosinski said dehydration can cause muscle cramps, heat exhaustion, or heat stroke.
Air quality is making things worse this week. The Maine DEP has issued an "orange" warning for those living in south coastal Maine.
High ozone levels make it "unsafe for sensitive groups," such as people with asthma.
"If we're in the yellow or orange area, it's reasonable to practice but you might have to be more sensitive to some of your athletes that might have asthma or breathing problem," said Dr. Bigonsinski.
The air quality warning is expected to continue until Wednesday.