The “NBC Nightly News” lost 700,000 viewers last week — Lester Holt’s first subbing for the disgraced Brian Williams.

The viewer hemorrhage was magnified by the fact it happened in the winter — traditionally the most competitive season for network newscasts.

That’s cold news to NBC’s ears.

“If you look at year over year, this makes NBC look really bad,” says ratings analyst Andrew Tyndall. “NBC had the Olympics last year, and they always get a boost.”

Last week (Feb. 9-13), “Nightly News” averaged 9.4 million viewers, down from the 10.1 million it averaged the week before (Feb. 2-6). The latter was the last week Williams anchored the 6:30 p.m. newscast before he was suspended for six months without pay for admitting he lied about being in a helicopter hit by enemy fire in Iraq in 2003, and Holt (above right) took over.

By comparison, with Williams behind the anchor desk, “Nightly News” averaged 11 million viewers and 11.6 million viewers, respectively, for the same two weeks last year.

“Whenever there’s a big change and a lot of publicity around that change — like the Williams situation — there’s going to be a lot of extra sampling,” says Tyndall. “Traditionally, viewers of one program check out the other one, so we can expect a lot of churning in the numbers.”

A network insider also points out the fact that “Nightly News” lost its viewers in one of the most competitive months of the evening-news cycle.

“News ratings are historically the lowest in summer and the highest in winter, when it’s cold and people stay indoors,” he said. “This is the most competitive time of the year . . . And keep in mind that [ABC’s] ‘World News Tonight’ was making inroads against NBC even before the Williams scandal.”

“Nightly News” did beat “World News Tonight” by 400,000 total viewers last week, but they tied with a 1.9 rating in the “money” news demographic of adults 25 to 54, with “Nightly” eking out a slim 50,000-viewer victory in that demographic.

NBC has launched an internal investigation in the wake of the scandal and stripped Williams’ name from the “Nightly News” title.