California’s heat wave raising health concerns ahead of sports-filled weekend

After days of record-breaking temperatures, weather officials are warning that California’s unusual October heat wave is expected to have a second peak this weekend, with millions of people facing another round of dangerous heat through Monday.

Temperatures are expected to remain 10 to 15 degrees above average for this time of year, with the San Francisco Bay Area and inland Southern California facing major to extreme heat risks. The National Weather Service defines extreme heat risk as “rare and/or long-duration extreme heat with little to no overnight relief,” likely to affect “anyone without effective cooling and/or adequate hydration.”

Across the majority of the Bay Area, officials warned of highs up to 105 degrees on Friday and Saturday, with even coastal areas reaching up to 95. The weather service warned that conditions there could have “life-threatening impacts or major impacts to commerce and travel.”

The weather may be a concern for the San Francisco 49ers’ NFL game against the Phoenix Cardinals at Levi’s Stadium on Sunday, whose 1 p.m. kickoff means fans and players will be exposed to the day’s most intense heat for hours.

Highs in Santa Clara are expected to soar into the mid-90s Sunday, according to Roger Gass, a National Weather Service meteorologist for the Bay Area. An analysis from SFGate found that Sunday’s game will likely be the hottest ever in the stadium, which opened in 2014. Uncomfortable — if not dangerous — conditions at the stadium, where the largest share of seats are positioned directly in the sun, have been a concern for years.

Read more: California’s heat wave to come ‘roaring back’ this weekend, with more record-breaking temps ahead

“We’re expecting [highs] anywhere from 93 to 96 degrees on Sunday,” Gass said. “It’s among the warmest” temperatures for this time of year in Santa Clara.

Earlier this week, San José Mineta International Airport — the closest official weather-monitoring site to Levi’s Stadium — hit 100 degrees for three consecutive days for the first time, among a slew of temperatures records set across the state.

Not far away, Stanford’s football team will kick off at 12:30 p.m. Saturday against Virginia Tech at Stanford Stadium, where highs are expected to reach the mid-90s.

“We are most concerned for people without adequate access to cooling,” Gass said. “Take frequent breaks in the shade if possible, don’t overexert yourself by any means.”

Heat deaths have become a growing crisis across California and the U.S. as climate change has made heat events more frequent, more persistent and more dangerous. Extreme heat has killed more Americans on average over the last three decades than hurricanes, floods and tornadoes combined, according to the National Weather Service.

Earlier this week, five students at a middle and high school cross-country meet in Riverside County required medical attention after experiencing “general weakness,” including three who were taken to the hospital for further evaluation, according to the Riverside County Fire Department, which responded to the scene.

Read more: How to stay cool and safe during California’s first heat wave of the summer

In June, a woman in San Diego County died while hiking on an unusually warm day, a death that appeared to be heat-related, local officials told KNSD-TV .

This weekend, Southern California’s coastal areas are mostly excluded from the major heat concerns, but in the Los Angeles and San Diego county mountains, valleys and foothills, weather officials warned tjat temperatures up to 108 are possible from Saturday through Monday, creating “a high risk for dangerous heat illness for anyone, especially for the very young, the very old, those without air conditioning, and those active outdoors.”

The highest temperatures across the state are forecast for the Coachella Valley and Palm Desert region, where highs could reach up to 112.

Officials across the state have opened cooling centers for residents and are working to increase awareness about the signs of heat illnesses.

“It’s important for Californians to continue taking action to protect themselves, including checking in on friends and neighbors, who can be vulnerable to heat when they are alone,” Amy Palmer, a spokesperson for California Governor’s Office of Emergency Services, said in a statement.

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This story originally appeared in Los Angeles Times.