The 49ers are a warm weather team but I have seen them win their share of cold weather games: 1970 in Minnesota in the playoffs (8 degrees), 1988 NFC Championship in Chicago (all you heard before the game was 'Bear Weather', 17 degrees, 26 below with wind chill), 2013 wild card at Lambeau (5 degrees F). Brodie was kind of a warm weather guy, but Montana and Kaepernick did grow up in cold weather states.
The warm weather Chargers folded against the Bengals in the 1982 freezer bowl. Seattle beat Minnesota in 2016 on a lovely day in Minnesota by Fargo standards.
The Dolphins are likely the least cold weather adapted team in football (they are built on speed also) so this particular one could get ugly. But history suggests anything can happen.