Cartire is correct and it's been a problem for this team for as long as I can remember. The climate is vastly different in Seattle and your bodies "acclimate" to it over time.
Roland, you are mistaken. I live in Alaska but my family is from Texas and when I go to visit them, the heat absolutely kills me and it feels like my life is at risk at 103 degrees. To the local residents it's nothing, but that's because they live there.
If you came to North Pole in March and it was 30 below, you would freeze your ass off. But those of us who just lived through -50 and -60 would think that it was downright balmy. But when I went to Orlando last April, it was 80-85 degrees and I had the A/C on nonstop.
The body takes time to adjust to heat AND humidity.
In our 2005 Superbowl year we went to Jacksonville early and it was the same thing, except not as hot as it was in San Diego. The Jaguars wore their white uniforms, and the Seahawks suffered in the heat. That's another thing you are overlooking. When you lived in those hot places, did you wear black on a hot summer day? No, you didn't.
This team was not prepared for the heat and humidity, and that's on Pete. "The Chargers have to play in that heat too!" is a silly statement. That's like Sean Payton telling Drew Brees "The Seahawks have to play in the cold and rain too."
San Diego is built for the heat, their players know how to hydrate days before the game, they know to get out in that heat and humidity, on that field and practice in it to acclimate. "You play like you practice." Well if you never practice in those conditions, it's a shock to your body.
The Chargers team had all the proper set ups for hydrating, cooling, and IVs. Our team didn't look nearly as prepared, holding a chalkboard over players heads to keep the sun off of them. How's that an even playing field?
If you're not from a place that has extreme weather conditions, you're not going to perform there optimally. Believe me, I've seen it a thousand times. I used to work on remote exploratory drill rigs on the North Slope and would see these guys from Oklahoma get off the jet with a skimpy little leather jacket and cowboy boots on the Arctic Coast in January. They would turn around and get right back on the plane.