Unscripted hits “American Idol” and “MasterChef Junior” teamed with Sunday’s return of “The X-Files” following a high-rated NFL playoff game to lift Fox to a decisive ratings victory in key demos last week.

Fox drew more young adults than the combined total of rivals CBS, NBC and ABC and also won easily in total viewers. It was the network’s second weekly victory of the season, and its first since a late-October frame when it aired five World Series games.

Overall, television viewing levels were higher than usual on Friday and Saturday due to a blizzard blanketing the East Coast. CBS had its highest-rated Friday of the season, with “Undercover Boss,” “Hawaii Five-0” and “Blue Bloods” all hit season highs in adults 18-49. Fox’s “MasterChef Junior” hit a high and led its Friday hour one week from its finale, while NBC’s “Dateline” hit a 10-month high.

One night later, ABC saw a nice start to its new “NBA Saturday Primetime” package as the Chicago-Cleveland matchup drew the basketball season’s largest audience (3.92 million) for any game excluding Christmas Day. Lifetime, meanwhile, drew a solid 3.6 million viewers for the premiere of “Unbreak My Heart”; the movie based on Toni Braxton’s memoir was cable’s No. 1 scripted telecast of the week in 18-49 (1.3 rating).

And on Sunday, even though better weather conditions may have tempted some along the East coast to venture out, huge crowds tuned in for the NFL conference championships. The AFC Championship on CBS between the New England Patriots and Denver Broncos drew a whopping 53.3 million viewers — the second largest for the event in 39 years and the largest ever for the early window on Championship Sunday — and the NFC Championship between the Arizona Cardinals and Carolina Panthers drew 45.7 million in primetime.

Fox followed its football game with the series return of “The X-Files” (6.1/19 in 18-49, 16.19 million viewers overall), which bagged the second highest rating for a series telecast on the Big Four this season — behind only a 6.7 for the season opener of the net’s “Empire.” Also contributing to Fox’s weekly victory was the special “MasterChef Celebrity Showdown” on Monday (1.5/4 in 18-49, 4.18 million viewers overall) and “American Idol” on both Wednesday (2.4/8 in 18-49, 9.22 million) and Thursday (2.4/8 in 18-49, 9.36 million).

Other highlights last week included some good news for NBC rookies “Superstore” (1.7/5 in 18-49, 5.66 million viewers overall), “Telenovela” (1.1/3 in 18-49, 3.87 million viewers overall) and “Shades of Blue” (1.4/5 in 18-49, 6.94 million viewers overall), each of which edged up in their third weeks.

Also for the Peacock, “The Blacklist” (1.6/5 in 18-49, 7.42 million viewers overall) matched its top rating of the season as it seems to be meshing well with “Shades of Blue” behind it. And in “live plus-3” estimates released yesterday, the third-year James Spader drama grew to a 2.8 rating in 18-49 (its highest since its season premiere) to move into a first-place tie for the night with Fox’s “American Idol,” which had beaten it by 0.8 in same-day rating.

At CW, “DC’s Legends of Tomorrow” had a strong bow Thursday (1.2/4 in 18-49, 3.21 million viewers overall) — rising in “live plus-3” to become the network’s fourth most-watched series premiere ever (4.93 million) and the second highest-rated premiere ever on the network (behind “The Flash”) in men 18-49 (2.3). The night also saw a solid third-season start for “The 100” (0.7/2 in 18-49, 1.88 million), which out-rated all of its season two episodes and helped give the net its most-watched Thursday in more than three years.

Earlier in the week, the CW had its highest-rated Tuesday of the season with the 2016 premiere of “Flash” (1.3/4 in 18-49, 3.41 million viewers overall) and a pair of DC specials, including a preview of “Legends of Tomorrow” (0.9/3 in 18-49, 2.05 million viewers overall).

For the second time in three weeks, Fox News Channel was the most-watched cable network for the week with 2.1 million in primetime. In addition to spikes due to coverage of the blizzard, “The O’Reilly Factor” averaged over 3.4 million viewers and 535,000 in the 25-54 demo — its highest-rated week since the San Bernardino terrorist attacks.

The Weather Channel also benefited from the snowstorm in the East, as it shot up week to week by 86% in primetime viewers (440,000 vs. 236,000) and nearly doubled its total-day audience (416,000 vs. 212,000).

At FX, the series premiere of Zach Galafiankis comedy “Baskets” (0.46 in 18-49, 1.035 million viewers overall) was a step up over last year’s bows of “The Comedians” (0.37 in 18-49, 0.88 million viewers) and “Sex Drugs & Rock & Roll” (0.35 in 18-49, 0.87 million). And in L+3, it became the top-rated basic cable comedy launch since 2014.

In its second week, Showtime’s “Billions” averaged 951,000 viewers for its regular timeslot and 1.19 million viewers for two Sunday airings. The drama’s premiere episode ended up being sampled by about 3 million people, the largest premiere tune-in ever for the premium cable network.

(Jan. 18-24, 2016; live plus same-day)

Adults 18-49 (rating/share)
Fox …………….  4.4/14
CBS ……………  1.5/5
NBC …………..  1.1/4
ABC …………..  1.1/3
UNI …………… 0.8/3
CW …………….  0.7/2
TEL ……………  0.6/2
TBS ……………  0.6/2
USA ……………  0.5/2
TNT ……………  0.5/2

Total Viewers (in millions)
Fox ……………….  13.20
CBS ………………   8.65
NBC ……………..   4.93
ABC ………………  3.97
FNC ………………  2.10
UNI ………………  2.10
CW ……………….  2.04
HGTV ……………  1.76
USA ………………  1.66
TBS ……………….  1.64

(Jan. 18-24, 2016; live plus same-day)

Adults 18-49
1.  NFC Championship: Arizona-Carolina (Fox), 15.7/42
2.  The X-Files (Fox), 6.1/19
3.  NCIS (CBS), 2.4/8
3.  American Idol-Thursday (Fox), 2.4/8
3.  American Idol-Wednesday (Fox), 2.4/8
6.  The Big Bang Theory-r (CBS), 2.2/8
6.  The Bachelor (ABC), 2.2/6
8.  Scorpion (CBS), 2.0/6
8.  Criminal Minds (CBS), 2.0/6
8.  Life in Pieces (CBS), 2.0/6
8.  The Goldbergs (ABC), 2.0/6
12.  NCIS: New Orleans (CBS), 1.8/6
12.  Supergirl (CBS), 1.8/6
12.  Chicago Fire (NBC), 1.8/6
12.  The Middle (ABC), 1.8/6
12.  60 Minutes Presents-r (CBS), 1.8/6
17.  2 Broke Girls (CBS), 1.7/6
17.  Black-ish (ABC), 1.7/6
17.  Mom (CBS), 1.7/5
17.  Mike & Molly (CBS), 1.7/5
17.  Law & Order: SVU (NBC), 1.7/5
17.  Superstore (NBC), 1.7/5

Total Viewers (in millions)
1.  NFC Championship: Arizona-Carolina (Fox), 45.74
2.  NCIS (CBS), 17.50
3.  The X-Files (Fox), 16.19
4.  NCIS: New Orleans (CBS), 13.30
5.  Scorpion (CBS), 11.60
6.  Blue Bloods (CBS), 11.55
7.  The Big Bang Theory-r (CBS), 11.08
8.  NCIS: Los Angeles-r (CBS), 10.64
9.  Hawaii Five-0 (CBS), 10.07
10.  60 Minutes Presents-r (CBS), 9.69
11.  American Idol-Thursday (Fox), 9.36
12.  Criminal Minds (CBS), 9.25
13.  American Idol-Wednesday (Fox), 9.22
14.  Life in Pieces (CBS), 8.78
15.  Supergirl (CBS), 8.77
16.  Mom (CBS), 8.49
17.  60 Minutes, 8 p.m.-r (CBS), 8.32
18.  Chicago Fire (NBC), 8.16
19.  Undercover Boss (CBS), 7.94
20.  The Bachelor (ABC), 7.56 

Source: Nielsen