TV ratings: ‘Under the Dome’ rules in return despite drop

CBS’ big summer series “Under the Dome” opened its second season well ahead of its competition Monday night, despite falling significantly from last year.

Season 2 of the science-fiction series based on the novel by Stephen King averaged 9.38 million viewers in its debut and earned a rating of 2.2 among key 18-to-49-year-old viewers, according to early numbers from Nielsen.

In both measures, it was broadcast’s highest-rated scripted summer telecast so far.

The introduction of the show last year, about a town trapped under a mysterious dome, delivered unusually strong numbers for a summer drama, though critics have begun to question the creative direction. Last year’s series premiere earned a 3.3 in 18-to-49, with the season at 2.8 (in that key young-adults demographic, a ratings point equals about 1.3 million viewers).

Elsewhere, Fox’s “Masterchef” notched a season high of 1.9 in 18-to-49, up 12% from a week ago, while the “24” reboot rose 7% to a 1.5. With an average of 1.7, Fox beat the otherwise-rerun CBS (1.6) in the key demo.

“The Bachelorette” held steady at a 1.5, followed by a slight increase from “Mistresses” (1.1). Meanwhile, NBC had the “Harry Potter: The Making of Diagon Alley” special, averaging 3 million viewers overall and a rating of 0.8. That was the only original for the Peacock on Monday night, which also had a rerun of “American Ninja Warrior.”

Follow Ryan Faughnder on Twitter: @rfaughnder