California faces heat, wildfire threats ahead of July 4th weekend

Much of California is facing a double whammy this week, with a dangerous heat wave and high fire risk at a time when millions of people will be out celebrating Independence Day.

Temperatures could reach 46 degrees Celsius in the Sacramento Valley, according to Kate Forrest, a meteorologist with the National Weather Service in the California capital. A heat alert will be issued for the region on Tuesday and is expected to last at least through Saturday.

“We’re expecting high heat and extreme heat risk across much of interior California,” Forrest said. “This heat is going to last for a long time.”

Meteorologists predict the heat wave will begin Tuesday in inland California, then spread to the Pacific Northwest and deeper into Southern California later in the week. Heat watches, warnings and advisories will blanket the West Tuesday, from southern Oregon to the low-lying desert of southeastern California, according to the National Weather Service.

The high temperatures are the result of a powerful high pressure system that will persist over the region.

“High-pressure systems force air down, causing it to compress and increase its temperature,” Forrest explained. “The air remains stagnant.”

State officials are bracing for the heat. Gov. Gavin Newsom has ordered emergency officials to activate the state operations center — his central command station in case of an emergency — his office said in a news release.

The heat could remain above 80 degrees Fahrenheit, even at night, in some places. By Friday, much of inland California will face “extreme” conditions, according to the HeatRisk map, a tool from the Centers for Disease Control and Prevention and the National Weather Service. The designation means the agencies expect impacts to health care facilities and infrastructure.

The area around Medford, Oregon, and other parts of the southern part of the state are also under an excessive heat watch through Saturday.

“If you have neighbors who don’t have air conditioning, check them a little more often,” said Brad Schaaf, chief meteorologist at the National Weather Service in Medford.

According to some forecast models, the Medford area could set a record for consecutive 100-degree days, Schaaf said. The area had 10 such days in a row in 1967.

Dangerous fire conditions will accompany the sharp rise in temperatures Tuesday in both states.

Pacific Gas & Electric said Monday that power outages were likely in 10 California counties Tuesday, given the high winds and dry conditions expected across Central California. The outages are designed to proactively reduce the risk of wildfires in areas where winds could knock down power lines or cause trees to fall on them. Outages are also planned for Wednesday.

But these preemptive outages risk leaving some communities without power when mercury reaches dangerous levels.

Forrest predicted up to a 45 percent chance of wind gusts over 35 mph in the Sacramento Valley region, with humidity levels that could drop into the single digits — a recipe for fast-moving wildfires.

Plants are dry and ready to burn, especially at elevations below 3,000 feet, she added.

“If the fire starts, it will spread,” Forrest said.

It’s a difficult time as July 4th celebrations kick off with fireworks.

“This is not ideal,” Schaaf said. “We want to urge everyone to exercise extreme caution when participating in activities that create sparks, such as using fireworks.”

The California Department of Forestry and Fire Protection is tracking 13 active fires, only four of which have burned more than 100 acres.

In the Southwest, wildfire season has already turned deadly. Two people were killed and 500 homes were destroyed in a blaze that tore through the community of Ruidoso, New Mexico, last month.

Climate change is increasing the likelihood of wildfires and heat waves. Last year, the nonprofit Climate Central calculated how the number of wildfire days in the United States has changed between 1973 and 2022. The analysis found that the Sacramento Valley is facing nearly two more weeks of wildfires, on average, than it did 50 years ago.

Heat waves, meanwhile, are occurring more frequently and lasting longer, according to data from the U.S. Environmental Protection Agency. U.S. cities used to experience an average of two heat waves a year; now, they typically experience six. These heat waves also last about a day longer, the data shows.