The Everest victory also made Urszula Tokarska of Toronto the first Canadian woman to climb the highest peaks on all seven continents, the Canadian Broadcasting Corp. reported.
Tokarska, 42, appears to have beaten Ottawa teacher Peggy Foster, who is on Everest in quest of the same distinctions, the report said.
Short of food and cooking fuel, Foster and her companions planned a last-chance push for the summit during the weekend.
Tokarska, climbing with a group of Americans, reached the highest point on Earth just after dawn Thursday, said an online diary posted by team leader Jim Williams of Wyoming.
Tokarska also has climbed Mount McKinley in Alaska, Aconcagua in Argentina, Elbrus in Russia, Kilimanjaro in Tanzania, Kosciusko in Australia and Antarctica's Vinson Massif.