I'm sure this isn't an actual disorder, but it should be, so I'm creating it.
Seasonal displacement disorder (SDD) is not to be confused with seasonal affective disorder (SAD) which makes you, as the name implies, sad during the winter. SDD is the condition wherein a person who is used to having seasons moves to the tropics and experiences one long summer that lasts for two years. This disorder may be characterized by decreased tolerance to even the slightest chill, a (probably incorrect) impression that one would actually enjoy being cold, and a general sense that time is standing still.
All joking aside, I am definitely suffering from seasonal displacement disorder. I often 'bundle up' when the sun isn't out now - even with temperatures in the 80s. I get weirdly nostalgic about fall and winter, when I know full well that back home I spend the entire winter complaining about the cold. And of course, I can never tell what time of year it is.
The nice thing is, like astronauts without gravity, people without seasons gain in freedom what they lose in structure. I've found that without actual seasons I tend to make up my own. So, for example, when I bought a nice summery tablecloth I decided to start a prolonged 'me-summer' and cooked lots of fresh salad, washed my car a lot, and had cool drinks on the balcony every other day. Recently decided that it should be winter time. I started wearing my sweaters inside again and cooking pumpkin dishes and chili and borscht. I rotated into the movie queue all the ones that remind me of winter (Girl with the Dragon Tattoo, Fargo, etc). I turned up the AC and started humming Christmas songs. I baked cookies. Bingo! Instant winter.
The even nicer thing about this is that I don't actually have to live anywhere cold. So if I want to go sailing and then sit outside at a restaurant for lunch and then read by the pool I can always take a holiday from my self-imposed holiday season for a few hours.
I get the feeling this might be hard to get used to actual winter when I get back to the states in December.