California becomes first US state to begin ranking extreme heat wave events

California Gov. Gavin Newsom recently signed into law a heat wave ranking system bill aimed at preparing the state for dangerous extreme heat events.

The law goes info effect in January 2023. The California Environmental Protection Agency has until Jan. 1, 2025, to create the yet-to-be-established statewide heat wave ranking system. Newsom also signed three other heat-related bills into law.

The January 2025 deadline gives the agency a window of just over two years to launch the ranking system. "I think two years is a reasonable deadline for us to really come up with a comprehensive approach, but of course, if we can do this sooner, we would definitely welcome that," said California insurance commissioner Ricardo Lara, who sponsored the heat wave ranking bill and issued the first California Climate Insurance Report.

Seville, Spain, which named the world's first heat wave—Zoe—in July, took 18 months to unveil its ProMeteo heat wave categorization system, according to the Adrienne Arsht-Rockefeller Foundation Resilience Center.

An oppressive heat wave broiled the Golden State early this month, marking one of the most brutal September heat waves ever recorded. California has been scorched by record-breaking heat for the past two years, including a 123-degree day in Coachella Valley in 2021.

"With lives and livelihoods on the line, we cannot afford to delay," Newsom said in a statement from the Governor's Office.

Here's what to know about California's plans to address extreme heat.

What is being proposed for the ranking system?

The bill outlines several factors to be considered in its creation, including:

• weather data, like maximum and minimum temperatures, and extreme heat event duration
• information and data on heat's health-related impacts
• measures of extreme heat severity
• locally relevant information like urban heat island effects or cooling measures
• public input

The bill states the heat ranking system will feature:

• Recommendations on thresholds or triggers for public policies that lower extreme heat's impacts to human health
• Metrics recommendations to measure short- and long-term extreme heat-related health effects

Lara said it's not yet clear what the ranking system will look like. "We don't want to be overly prescriptive in the actual law, we want to allow for the experts to be able to come up with a system that's going to make sense in California," he said.

What does the extreme heat ranking bill mean for Californians?

The heat wave ranking system would bolster existing heat warning systems by categorizing heat waves based on their human health impacts, said Kathy Baughman McLeod, director of the Adrienne Arsht-Rockefeller Foundation Resilience Center, in a statement from the California Department of Insurance.

The bill is part of the Arsht-Rock Resilience Center's efforts to pilot categorizing heat waves in parts of the U.S. and Europe. "People do not have to die from heat, and this groundbreaking legislation goes a long way toward protecting 40 million Californians," McLeod said.

California's lower-income communities get disproportionately hit with extreme heat's affects, said assembly member and bill coauthor Luz Rivas (D-Arleta) in a statement. She added the system will ensure Californians get properly notified of the severity of upcoming heat-related weather events.

"We see the impacts to crumbling infrastructure, human health and air quality, and to be able to say California is leading the world in fighting climate change and the deadly effects of extreme heat is something to be really proud of," Lara told U.S. TODAY.

What other heat-related bills were signed into law?

Newsom signed three other heat-related bills into California law:

• AB 2420 requires California's Department of Public Health to research extreme heat's adverse health effects on people shortly before they give birth or just after pregnancy. The department will also "develop guidance for safe conditions and health considerations for pregnant people and infants," the bill states.
• SB 852 gives California's cities, counties and special districts the green light to form "climate resilience districts" that can finance projects to combat extreme heat, sea level rise, wildfire and other climate threats.
• AB 1643 requires the state's Labor and Workforce Development Agency to create a committee that studies how heat impacts California's workers, businesses and the economy.