WGN (Photo: Museum of Broadcast Communications)

This means war: For the first time in 35 years, Chicago has a genuine four-way battle for nightly news viewers straight up at 10 o’clock.

Monday marked an auspicious debut for WGN-Channel 9’s half-hour newscast at 10 p.m., a return to competition the Tribune Media flagship station relinquished in 1980.

Opening night saw WGN finishing third in the ratings behind ABC-owned WLS-Channel 7 and NBC-owned WMAQ-Channel 5. CBS-owned WBBM-Channel 2 trailed in fourth place. WGN also beat CBS 2 in all key demographics at 10 p.m., including adults between 25 and 54, adults between 35 and 54, and women between 25 and 54.

As advertised, superstar weatherman Tom Skilling occupied center stage in the new 10 p.m. showcase with a forecast that took up a substantial part of the newscast’s first segment. News anchors Mark Suppelsa and Micah Materre were genial and professional, as usual.

WGN’s long-established one-hour newscast at 9 p.m. continued its customary dominance over Fox-owned WFLD-Channel 32.

Here are Nielsen ratings and shares for all television households at 10 p.m. Monday:

• ABC 7: 7.1 rating; 12.0 share

• NBC 5: 6.2 rating; 10.5 share

• WGN: 2.9 rating; 4.9 share

• CBS 2: 2.5 rating; 4.3 share

Here are Nielsen ratings and shares for 25-to-54 viewers at 10 p.m. Monday:

• ABC 7: 2.8 rating; 7.2 share

• NBC 5: 2.8 rating; 7.2 share

• WGN: 1.6 rating; 4.0 share

• CBS 2: 0.7 rating; 1.9 share

One rating point represents 34,752 households; share is percent of sets in use.

Devotion to Accuracy Department: Fox 32 aired a 10 p.m. newscast, "The Ten," from April 2007 to September 2009.

Mark Suppelsa, Dan Roan, Tom Skilling and Micah Materre