I went and looked at the average highs in Seattle during football season, coming up with 56.75 degrees. Seattle traveled to San Diego last weekend & watched the game, the field temperature was ~120 degrees. That's more than double the average Seattle regular season temperature & obviously put Seattle at a great disadvantage being from a much cooler climate. The Chargers also went ahead during the hottest part of the day & then no one did as much in the second half.
So just to be clear here, last week was a extreme weather scenario that really favored San Diego as the warm weather team.