California’s brutal heat wave will coincide with July 4 wildfire dangers

A brutal, long-lasting heat wave is threatening to wreak havoc across California this week as sweltering conditions, power outages and a sharp increase in fire dangers coincide with July 4th celebrations.

The dangerous weather event is expected to last for days with little break. Beginning Wednesday, parts of the state will be subject to extreme heat danger levels reaching the highest level on the National Weather Service index that will last through Sunday or longer. In some areas, life-threatening triple-digit temperatures can persist for more than a week.

This will be a severe, prolonged, potentially record heat wave that could have major impacts across much of California, climate scientist Dr Daniel Swain said during a broadcast discussion of the heat event on Monday. Longer duration will add to the potential impacts and intensity, especially since some relief can be expected even after the sun goes down. It just won’t even get cold at night, he said.

While central and northern California are expected to bear the brunt of this event, areas in the southern part of the state will also be cooking. Heavily populated centers and rural agricultural enclaves alike could see record highs during the day as well as record highs at night. In the Central Valley, the states agricultural heartland, temperatures are expected to hover near 110F during the week without dropping below 70F.

Forecasters have warned that the dangerous weather conditions will pose health risks to the majority of the population, especially those unable to access cooling. These are places where, yes, it’s hot in the summer, but it’s not often hot like this, and certainly not for this length of time, Swain said.

Extreme weather will also set the stage for new wildfires that could quickly turn into inferno. A fairly wet winter left landscapes across California covered in grasses that quickly dried up as the weather warmed. Yellowed hills and valleys are thick with fuel for fast-burning brush fires. Even the deserts, usually barren at this time of year, are now ready to burn. “Unfortunately, I’m not using the term if there are fires because I think it’s inevitable during this event,” Swain said.

Fire hazards always increase on the Fourth of July, when hot, dry weather coincides with explosive celebrations. Across the country, more than 18,500 fires are started on average because of Independence Day celebrations, whether from misfired fireworks or misbehaving campfires. But as the temperatures rise, so do the risks. Both fire activity and fire behavior this week are likely to be extreme, and new fires may become difficult to contain.

It’s going to be a challenge both day and night, so the message is prevention, said Cal Fire Deputy Chief Nick Schuler. The agency is at maximum staffing levels to prepare for what is expected to be an extremely busy week, stretching into an extremely busy summer. Already, California has seen more than 131,400 acres burned, with months to go before the dangers peak.

The bottom line is that 95% of fires in California are human-caused, and most of them are preventable, Schuler said, noting that careless baking, a spark from a trailer chain hitting the road or even a cleaning of Intentional brushing can quickly turn into a disaster during the hottest days.

But the heat will not only amplify the dangers and intensity of fires this week, it will also work dry out more vegetation that can help fuel future fires.

A scorching start to July only adds to what has been an unusually hot spring. May wrapped up the 12th consecutive month of record heat around the world. The trend continued into June in many places, including parts of California, and summer is on track to be a scorcher. 2023 was declared the hottest year on record, and 2024 could quickly claim the title.

The heat draws moisture from vegetation and soil, said Dr. Alexander Gershunov, a research meteorologist with the Scripps Institution of Oceanography, noting that while this may be the worst heat wave to hit California this year, it will life far from the last.

While individual weather events can be difficult to link to global warming more broadly, heat waves are the ones most directly affected by the climate crisis, Gershunov explained. Driven by human-induced warming, heat waves are increasing in both intensity and frequency, but they are also lasting longer and covering wider areas than before. This has only increased their potential to affect human health and burden systems.

Heat waves are certainly the extremes of weather that are affected by climate change steroids, he said, explaining that the effect is similar to an athlete taking performance-enhancing drugs.

Summer weather has been extreme before, but it’s about to get hotter.

The trend is toward more frequent, more extreme and longer heat waves around the world, he said. California is certainly no exception.

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