The Fairbanks Daily News-Miner reported the race was scrapped Sunday morning.
Race marshal Greg Parvin said the trail between Meier's Lake and Sourdough had unusually deep snow conditions, with high winds and bitter cold.
Meier's Lake is about 75 miles into of the race, a qualifier for the Iditarod Trail Sled Dog Race and the Yukon Quest International Sled Dog Race.
Organizers said temperatures were consistently 45 to 50 below zero and the cancellation was done in the interest of the dogs, mushers and race staff.
The Copper Basin 300 begins at Chistochina, loops to Paxson then travels south to Meier's Lake, Sourdough, Lake Louise and Glennallen.
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