LOS ANGELES — TV viewers will see a lot of Oscar winner Halle Berry at an unusual time of year when CBS airs the 13-week sci-fi drama “Extant” starting in July.

Instead of introducing the series during the traditional TV season that runs from September to May, CBS will air “Extant” during what used to be rerun time, when school is out, families are on holiday and there’s less interest in TV.

Those days are gone. With more viewers watching on demand, on Netflix or tuning in to cable shows that debut year-round, TV programmers are ordering short “event series,” such as “Extant” and a planned revival of “Roots,” the famous miniseries from the 1970s. They’re hiring big stars to draw audiences and advertising, and break up the daily TV routine, just as shows like “Holocaust” and “Shogun” did years ago.

“It makes sense on a lot of different levels,” said Todd Gordon, an executive vice president at Magna Global, the media buying arm of the advertising company Interpublic Group of Cos. “You can attract different talent for a 13-episode run than for a full season. We all have busy lives. I don’t have the endurance for a 20-episode season.”

The revival of the short series is evident in New York this week at the so-called upfronts, where broadcast and cable networks are presenting their shows to advertisers for advanced commitments.

Fox, which released its 2014-15 lineup last week, unveiled two, 10-episode series: “Gracepoint,” based on the British TV murder-mystery “Broadchurch,” and “Wayward Pines,” from M. Night Shyamalan, who directed “The Sixth Sense.”

The network, part of 21st Century Fox Inc., is airing “24: Live Another Day,” a 12-episode revival of the action-espionage series featuring Kiefer Sutherland that ran for eight seasons through 2010. That series is certain to be profitable with airings on Fox and Amazon.com, according to Chase Carey, chief executive officer of 21st Century Fox.

Fox Entertainment Chairman Kevin Reilly said short-run shows with definitive endings will help the network draw audiences year-round.

“We’re making Fox a 24/7, 365-day experience,” Reilly said at his presentation to advertisers.

NBC, part of Comcast Corp., touted two new short series at its presentation Monday, including “A.D.,” a Biblical epic from reality TV producer Mark Burnett that opens with the crucifixion and resurrection of Jesus.

“How’s that for a pilot?” Robert Greenblatt, chairman of NBC Entertainment, said at the event. NBC is leading the prime- time ratings in 18-to-49 this season for the first time in a decade, with help from professional football, the Winter Oympics, “The Voice” and “Blacklist.”

Conventional television faces growing competition from alternative programmers such as Netflix, Amazon.com and YouTube.

CBS’s deal for “Extant,” a Steven Spielberg-produced sci- fi featuring Berry as an astronaut trying to reconnect with her family, and the second season of last summer’s “Under the Dome,” were financed in part by Amazon.com, which is releasing the shows online for customers of its Prime service.

Cable networks, which pioneered year-round programming, are also producing more short-run programs.

A+E Networks, owned by Walt Disney Co. and Hearst Corp., is working on a remake of “Roots,” the 1977 miniseries that set the standard for short dramatic programs and ranked as one of the most-watched in history.

The company last year aired the miniseries “Bonnie &Clyde” on three of its channels, A&E, History and Lifetime, attracting almost 10 million viewers on its first night.

The company’s networks pool their marketing dollars to promote their special projects, according to Nancy Dubuc, chief executive officer.

“The entire company is going to focus on ‘Roots,’” Dubuc said April 30 at the Milken Institute Global Conference in Beverly Hills, California. “That is event television.”