One of the privileges of being a fiction writer is that one has license to reinvent the world. Don't like something about reality? Adjust it.
For many years, I've wondered why Midwinter, the Winter Solstice, doesn't actually fall in the middle of winter but instead marks the beginning of winter. In my region, we can get snow in October and November doesn't look much like autumn. Nor does early March, with crocuses popping up, look much like winter. The conventional seasons just seem wrong to me.
Therefore, when creating the Ælven culture for my new fantasy series, I messed with the calendar. I rearranged things so that Midwinter and Midsummer land in the middle of their appropriate seasons. This puts the spring and autumn equinoxes in the middle of those seasons, which pleases me very much.
I like this system so much I made a 2009 calendar using it. If you'd like a free copy, send me your mailing address via my Ælven calendar page. While you're on the site have a look around for more about the Ælven, and about my first Ælven novel, The Betrayal.