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It's not just Cillian Murphy's beautiful yet tortured blue eyes driving people to the movies this summer.

In Southwestern markets like Los Angeles, Phoenix, and Tucson, Arizona, where daily temperatures have consistently surpassed 100 degrees Fahrenheit this summer, audiences are flocking to movie theaters to beat the heat, CNN reported.

It's Getting Hot in Here

While Christopher Nolan's Oppenheimer and Greta Gerwig's Barbie were already on track to captivate audiences and bring in a combined box office of more than $1 billion, heat waves are providing another boost.

Many moviegoers have enjoyed the unofficial double feature dubbed "Barbenheimer," allowing them to spend at least five hours in air-conditioned theaters:

  • Boxoffice Pro analyst Shawn Robbins told CNN that US ticket sales have raked in $5.8 billion so far this year, $1 billion more than last year. While film quality and marketing plays a major role, "as we get into July and August, the dog days of summer, the heat can be a determining factor," he said.
  • And it's not just the biggest films attracting audiences. In June, the Loft Cinema in Tucson hosted its annual 12-hour sci-fi slumber party, and program director Jeff Yanc told CNN it was one of the event's most attended years. But this wasn't your typical Star Wars or even Planet of the Apes-bolstered marathon. It was a niche selection including classics like Matango: Attack of the Mushroom People, The Last Starfighter, and Johnny Mnemonic.

The AC's history: Before widespread adoption of air conditioning among movie theaters, summer was actually Hollywood's lull period. The summer blockbuster as we know it didn't exist in the days of Gloria Swanson, John Ford, and Charlie Chaplin. Once theaters began installing cooling systems in the 1920s, they opened their doors so that cool breezes would hit people walking by, subliminally tempting them to buy tickets, Salvatore Basile, author of Cool: How Air Conditioning Changed Everything, told CNN. Today's theater ACs are relatively silent, and yet we still can't hear half the dialogue in a Nolan movie.