Does anyone else do this? Not exact dates, but general times of year.
Examples from me: there is always a day, with really cold, fresh air but blue sky, and bright sun, in maybe January or February, that reminds me of stepping out of my hotel room in New York about 5 years ago. Every year.
There is always a day in summer when it's kind of muggy but not enough to get on your nerves, a really pleasant kind of warmth, and I'll be out at night and there's a very... summery... atmosphere in the pub or wherever you are, and it reminds me of the first ever $hit gig where everyone went crazy and the party went on until dawn and everyone was dancing and snogging and stuff.
There are a few more, some less fun than those two. They are like... memory echoes, or something, of what happened at a certain time of year, that repeat every year when the conditions or circumstances are the same.