Wow, I am continuously amazed at what you west coasters have to go through (specifically power for this topic). We keep our thermostats at 70 in the summer and I kick the bedroom down 1 degree at night just to chill the air before bed. I couldn't imagine 78-80!
Agree, this is a humidity issue. We lived in the Midwest for 7-8 years. Low 80s can feel surprisingly hot (to an uninitiated Californian). I remember when new to St. Loius, went to a Cardinals game and it was 82F after the sun set and was expecting to feel relief, but everyone was still sweating and uncomfortable in t-shirts and shorts.Part of the reason you run home colder in the Midwest is because of the humidity. The A/C is as much a dehumidifier as anything else. Until we moved to the east coast and midwest as a native Californian I had never heard of a dehumidifier or saw an A/C unit with water running out of it. It all seemed very strange to me.
I leave the house at 80 and wander around with shorts and a t-shirt. Any below 76 and I need to put on a sweatshirt.
78-79F here in dry CA feels quite comfortable.