TV ratings: 'Under the Dome' rules in return despite drop

TV ratings: 'Under the Dome' rules in return despite drop
Dean Norris in "Under the Dome," which aired its Season 2 premiere Monday night. (Brownie Harris / CBS)

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