The NFL’s highest rated TV window got off to its worst start in more than a decade, though breaking weather coverage may have played a role.

The Week 1 NFL national window, featuring Seahawks-Packers in 89% of markets, had a 12.7 rating and 22.8 million viewers on FOX Sunday afternoon — down 18% in ratings and 17% in viewership from last year (15.5, 27.5M) and down 6% and 2% respectively from 2015 on CBS (13.5, 23.3M). Last year’s window featured Giants-Cowboys and the 2015 telecast featured Ravens-Broncos.

The 12.7 rating is the lowest for the Week 1 NFL national window in 14 years, since FOX posted a 12.5 for coverage featuring Falcons-Cowboys in 2003. The previous low over that span was a 13.0 for coverage featuring Cowboys-Browns in 2008, also on FOX.

It was the least-watched Week 1 national window since that 2008 telecast, which had 20.9 million.

Earlier in the day, regional action featuring Philadelphia-Washington in 51% of markets had a 6.6 rating and 11.3 million viewers — down 28% in both measures from last year (9.2, 15.8M) and down 27% and 24% respectively from 2015 on CBS (9.0, 14.9M).

It was the lowest rated and least-watched Week 1 window on broadcast television since the first half of that 2008 doubleheader on FOX (5.1, 7.9M).

Competing news coverage of the approaching Hurricane Irma may have affected the numbers. The Weather Channel averaged 4.3 million viewers from 1-8 PM ET Sunday (on the comparable day last year, the network’s top hour had 284,000).

[Wknd. numbers via ShowBuzz Daily 9.13]