When I got back to San Francisco and went out the first night, I was unbelievably cold. Everybody was giving me crap for being a pussy, especially after just getting back from Moscow, where one night it was -26C and it didn't feel as cold as San Francisco's 6C. I figured it was wind or humidity? But then I was also freezing at home, with the thermostat on normal temperature.
But then this morning I woke up with a sore throat, mild cough, congestion/phlegmy, and heat swings of super hot and super cold.
So mystery solved... I'm just sick. It's not actually cold outside.