KRASNAYA POLYANA, Russia — With the Winter Olympics melting under a heat wave, the effects could be seen Thursday from the coast of Sochi, where spectators were spotted sunbathing, to the mountains high above the city, where cross-country skiers raced in sleeveless jerseys. The balmy weather has forced changes in competition schedules, sent workers scrambling to harden the slushy snow and made Olympians reconsider what to wear for their warm-weather winter sports.

“You sit outside in a T-shirt and shorts — that’s not winter,” said Christoph Sumann of the Austrian biathlon team. “You don’t know what to wear for the race.” He settled on the thinnest T-shirt he could find. A teammate, he said, wore nothing beneath his racing uniform.

“It’s absolutely too warm for me,” he said. “I’m a winter guy.”

So far, these Olympics have not been a good fit for those who like their Winter Games wintry. It has not snowed since the Olympics began last week, and most days have brought bright sunshine and springlike temperatures.

“I’ve never seen it this warm at a Winter Games,” said Max Cobb, a senior official with the International Biathlon Union, who has attended every Winter Olympics since 1992. Cobb was in constant radio contact with the crew spreading salt, meant to turn the slush into water, then back into ice.