But members of the Fire Brigade Employees Union, which represents firefighters in Australia, said at a news conference last week that it was “bewildering” that the government expected volunteer firefighters to work for months on end without compensation.

As they do so, the firefighters are risking their lives in the face of blazes that are growing larger and more intense as the country gets hotter and drier. That danger was tragically illustrated last week when two firefighters battling a blaze in a town southwest of Sydney were killed when their truck rolled over.

David Smart, captain of the volunteer firefighters in the Kangaroo Valley, 100 miles south of Sydney, said that his brigade was taking steps to manage the increased demands. The firefighters were cycling shifts to try to avoid fatigue, he said, but the long days still wore on them. And then there is the emotional trauma of seeing houses and bush land destroyed, he added.

“I think everyone is very stressed,” he said. “People are tired. It’s been going for weeks on end.”

The burdens that fell on volunteer firefighters were lighter in the past, many said. In previous years, fires were more spread out through the year, said Brad Kelly, deputy captain of the Ingleside Fire Brigade, north of Sydney, which tackled a blaze on Monday.

“They weren’t just one big continuous line of activity through that whole time,” he said.

On a recent shift, firefighters did not return home until 4 a.m. “If a house is being impacted, you’re not going to walk away from it,” Mr. Kelly said.