Photo: The Canadian Press

The Encino wildfire, in Sonoita, Ariz. 

An extreme heat wave in the Southwest U.S. made the fight against a series of wildfires more difficult Wednesday, including one that has destroyed at least four homes in an Arizona town known for its wineries, authorities said.

Temperatures in parts of Arizona, California and Nevada soared to nearly 49 C this week, creating problems for firefighters. In California, two firefighters were treated for heat-related injuries as they battled a blaze in the San Bernardino Mountains east of Los Angeles.

In New Mexico, authorities say a brush fire destroyed sheds and vehicles on private property and sent two residents and a firefighter to the hospital for smoke inhalation and other minor injuries.

In Arizona, about 100 firefighters battled a five square kilometre blaze believed to have been ignited by lightning Tuesday in triple-digit temperatures in Sonoita. None of the wineries dotting the area was threatened.

Evacuations were lifted Wednesday evening after rainfall helped control the fire.

Firefighters across Arizona are battling about 30 blazes, making resources scarce, De Wolf said. He said he was asking Gov. Doug Ducey to help cover the financial costs of battling the fire.

Fires are burning throughout the Southwest, including one in Utah that forced the evacuation of more than 700 people and shut down part of a state highway.