Seasons and Hermetic Dates
It's a small matter, but often it comes up in Ars Magica that it matters exactly when a season begins and ends. To avoid confusion and aid role-playing I present this quick guide.
Seasons and Quarter-Days
All seasons begin on a quarter-day (an equinox or solstice). The quarter-day is considered to be the first day of the season, and the day begins at sunrise for magical and ritual purposes.
- The Winter season begins on the winter solstice, approximately Dec. 21 or 22
- The Spring season begins on the vernal equinox, approximately March 20 or 21
- The Summer season begins on the summer solstice, approximately June 21 or 22
- The Autumn season begins on the autumnal equinox, approximately September 22 or 23
Hermetic New Year
I view the Order of Hermes as a medieval organization, not a classical one. Therefore it adheres to the same Julian calendar as the Mythic Church and the rest of Christendom. While the Romans celebrated New Year's Day on January 1, medieval people in many countries started the new year on the Feast of the Annunciation (March 25). If the local Tribual follows the convention of the mundanes in its region, the new year begins near the start of spring (rather than in early winter). (Official Ars Magica products are silent on this detail.) In the Saga of Stranggore, we use March 25 as the new year's date.
Technically, the first few days of the Spring season (approximately March 20-25) fall in the old year, and so Spring spans the year boundary. The overlap is only a few days, so the Spring season is associated with the new year which begins during its span. For example, the Spring season spanning March 20, 1193 to June 21, 1194 would be considered Spring of 1194 -- even though its first few days were the last days of 1193.
It is often useful to magi to time their rituals and laboratory work to coincide with astrological events. The most prominent of these are the sun entering a new sign of the Zodiac (though the lunar Zodiac is only slightly less important). See the Sun sign dates at Wikipedia for a table that says when each astrological sun sign begins and ends.