Tv1, 2 & 3 died. They just wouldn't come up at all. On the day we hit 26C. Sky claimed they couldn't get anyone out for 6 weeks. We were able to insist that we knew it was definitely a Sky fault and demanded to see a tech asap.
It was the old dish fittings. The same ones that people here run into issues with for rain fade on hot days. Ours were two generations behind and had been failing for well over a year.
Long story short - if you get rain fade and signal loss on hot days call Sky and get a tech out. Its a known problem with the previous two generations of dish and is quickly and easily fixed.