NBC was wise to save “Windfall” for a summer burnoff. After a somewhat promising debut two months ago, the drama about a group of lottery winners has fallen hard.

Last night “Windfall” hit a series low with a 1.6 overnight rating among adults 18-49, down 52 percent from the 3.3 it averaged in its June 8 premiere.

The show was also nearly one-third off its season-to-date average of 2.3 and down 0.2 from the previous week’s 1.8 average.

NBC originally planned to premiere “Windfall” last spring but decided to delay it until summer at midseason. Though the Luke Perry program received decent reviews when it debuted, it simply couldn’t hold that audience.

It’s one in a long series of summer broadcast dramas, most recently including Fox’s “The Jury” and “The Inside,” that have struggled. Though dramas tend to do well on cable during the hot months, new ones rarely do well on broadcast, where viewers are used to seeing repeats and reality shows.

Meanwhile, using just that, CBS led for the night at a 2.7 rating and 8 share in 18-49s, followed by Fox at 2.5/8, ABC at 2.1/6, NBC at 1.9/6, Univision at 1.8/5, WB at 0.8/2 and UPN at 0.7/2.

At 8 p.m., CBS was No. 1 at 2.6 for "Big Brother 7: All-Stars," ahead of Univision's "La Fea Mas Bella" at 2.2, NBC's reruns of "My Name Is Earl" and "The Office" at 1.9, Fox's pair of "That '70s Show" repeats at 1.7, ABC's "Grey's Anatomy" rerun at 1.6, WB's "Smallville" rerun at 0.9 and UPN's "Everybody Hates Chris" and "Love, Inc." reruns at 0.8.

At 9 p.m., Fox led at 3.2 for "So You Think You Can Dance," followed by CBS at 2.8 for a "CSI" repeat, NBC at 2.3 for "America's Got Talent," ABC at 2.1 for another "Grey's" repeat, Univision at 1.7 for "Barrera de Amor," WB at 0.6 for a "Supernatural" repeat and UPN at 0.5 for "Eve" and "Cuts" reruns.

At 10 p.m., CBS's "Without a Trace" repeat led at 2.8, followed by ABC's "Primetime" at 2.5, NBC's "Windfall" at 1.6 and Univision's "Aqui y Ahora" at 1.5.

Among households, CBS won the night at a 6.2 rating and 11 share, ahead of ABC at 4.5/8, Fox at 3.9/7, NBC at 3.7/7, Univision at 2.2/4, WB at 1.4/2 and UPN at 1.0/2.