BATLOW, Australia — Most of the fires Michael Blenkins has put out since becoming a volunteer firefighter in the 1980s required little more than rushing to a nearby farm and hosing down ankle-high flames. In and out in maybe an hour, then back to work as a teacher.

When he persuaded his eldest son, Edmund, to join the rural fire brigade at 16, he thought less about danger than camaraderie.

But in Australia, climate change and the huge fires it fuels have obliterated the old normal. Instead of the usual three or four days a year, the Blenkinses have been fighting fires around their mountain town, Batlow, on and off for a month. They have repeatedly put in 12-hour days. And the danger has been immense: On Jan. 4, they nearly died in a firestorm.

“There were flames kicking up everywhere,” Mr. Blenkins, a formal man with an even manner, said one recent day, a dress shirt peeking out from under his firefighter gear. “It was like the Titanic — we thought we were prepared to handle it, and we weren’t.”