(Reuters) – Firefighters are gaining momentum as they battle several wildfires that have destroyed dozens of homes and forced the evacuation of thousands of residents in California.

Across the state, milder weather over the last couple of days has helped firefighters to hold the line against several blazes, allowing them to lift evacuation orders for residents forced to flee their homes.

Temperatures are expected to fall this week in parts of the state, the National Weather Service said, after scorching heat, high winds and low humidity fanned dozens of fires this summer in a particularly intense fire season across the U.S. West.

“The weather is starting to cooperate, so it’s letting firefighters get the upper hand on the fires,” said Lynette Round, a spokeswoman for the California Department of Forestry and Fire Protection, called Cal Fire.

U.S. wildfires have already burned more than 3.3 million acres (1.3 million hectares) this year, more than the annual average of about 2.6 million acres over the past 10 years, according to the National Interagency Fire Center.

One person has been killed and three firefighters injured in a wildfire on the California-Oregon border. That blaze, the Klamathon Fire, has torched 36,500 acres (14,770 hectares) and destroyed 82 homes since erupting on Thursday.

Shifting wind patterns remained a concern, but that fire was not expected to grow significantly overnight, a spokesman for Cal Fire said.

In western Nevada, a fire weather watch will be in effect on Wednesday as winds up to 50 miles (80 km) per hour and thunderstorms with lightning are expected in the area.

Elsewhere in the U.S. Southwest, dozens of active fires remained burning, including the 107,900-acre Spring Creek Fire, which is on pace to become the second-largest fire in Colorado’s history, according to the Denver Post newspaper.

“Near critical fire weather conditions are possible across portions of eastern Colorado Tuesday afternoon,” the National Weather Service said in an advisory.

Showers and thunderstorms are also in the forecast for parts of the region through Wednesday, the weather service said, warning of lightning and gusty winds that could create and fan wildfires.

(Reporting by Brendan O’Brien in Milwaukee, editing by Larry King)