Temperatures across the southwestern US, including California, began rising on 20/8 and are expected to persist through the weekend, as extreme weather conditions spread north along the Pacific Coast.

The National Weather Service (NWS) has issued warnings about the triple threat of thunderstorms, extreme heat, and wildfires, urging residents in California and surrounding areas to prepare.

A resident buys a cooling drink in Los Angeles on 19/8. Photo: AP

A resident buys a cooling drink in Los Angeles on 19/8. Photo: AP

The NWS predicts temperatures could exceed 43°C in the southwestern deserts and surpass 38°C throughout Southern California. "These dangerous temperatures will pose a significant threat to anyone without effective cooling and adequate hydration," the agency warned.

Daily temperature records in Los Angeles and several areas in Arizona and Nevada could be broken during this heatwave. The sweltering conditions are expected to persist after sunset, making for uncomfortable nights.

"Overnight low temperatures may reach unprecedented highs across a wide area" in the western US, climate scientist Daniel Swain stated.

High nighttime temperatures create challenges for firefighting efforts and pose health risks to those without access to air conditioning.

"The most notable aspect of this heatwave is the prolonged overnight heat, with minimum temperatures not falling below 21-26°C", Swain said.

While August heatwaves are common in California, the abrupt shift could pose health problems for those not yet acclimated to high temperatures this year. Outdoor workers, the homeless, children, and the elderly are particularly vulnerable.

Heat warnings across the southwestern US on 20/8. Graphic: SFChronicle

Heat warnings across the southwestern US on 20/8. Graphic: SFChronicle

Extreme heat, often called a "silent killer," is the leading weather-related cause of death in the US. Climate change and urban heat island effects contribute to longer, more intense, and widespread heatwaves.

Many areas affected by this week's heatwave, including parts of Los Angeles and Ventura, face an elevated risk of wildfires. Drought conditions across Southern California have left vegetation dry and flammable. According to the NWS, this heatwave could further desiccate vegetation, leading to rapid and extensive fire spread.

"The wildfire risk in California may peak between 21/8 and 23/8", Swain noted.

As a preventative measure, California Governor Gavin Newsom has mobilized resources to high-risk areas, including 32 fire engines, 9 water tenders, 9 bulldozers, 5 helicopters, 9 fire crews, 13 coordinating staff, and two incident management teams.

The US has recorded over 44,400 wildfires this year, approximately 16% higher than the 10-year average. The peak fire season is not yet over, particularly in California, where the hot, dry Santa Ana winds typically blow during the autumn months.

Hong Hanh (According to The Guardian)