Runic calendars, Norse months and the two seasons
A runic calendar is a stick or board, often of wood, with the days of the year carved along it in runes. In Swedish it is a runstav; the Norwegian primstav does the same with pictures instead. Several thousand survive, most of them from the 16th and 17th centuries. The only medieval runic one is the Nyköping staff, found in 1964 and dated to the mid or late 13th century; the oldest dated Norwegian primstav is from 1457.
How it works
The first row repeats the first seven runes of the Younger Futhark, f u th o r k h, 52 times round the year. They work like the Sunday letters A to G of Latin calendars: once you know which rune falls on Sunday in a given year, every weekday follows.
A second row marks the new moons. The moon’s phases fall on nearly the same dates every 19 years, and each year of that cycle has its Golden Number. On the stick the 19 numbers are the sixteen runes of the Younger Futhark plus three extra signs called árlaug, tvímaðr and belgþórr. In year seven of the cycle, say, the new moon falls on every day marked with the seventh rune. The scholar Ole Worm described the three extra signs in 1636.
A Christian tool
This is church reckoning, not pagan star lore. The Golden Numbers and Sunday letters serve the Easter calculation, and the sticks mark saints’ days and church feasts. The runes are simply the local alphabet, used as numbers. Large collections are in the Nordiska museet in Stockholm, the Småland museum and the National Museum of Denmark.
Two seasons and twelve months
The old Icelandic year had two halves, summer and winter, called misseri. A 13th-century text says it simply: two misseri make a year, winter and summer. Summer began on a Thursday, and the first day of summer is still a public holiday in Iceland; winter began on a Saturday.
According to Ari Þorgilsson’s Íslendingabók, written between about 1122 and 1133, the year once counted 364 days, exactly 52 weeks, and people noticed summer slipping back towards spring. In the mid-10th century a man called Þorsteinn surtr proposed adding a week every seventh summer. The year settled into twelve months of 30 days, four extra nights, and the leap week when it was due.
Snorri gives a full list of month names, among them Gormánuðr, Frermánuðr, Þorri, Gói and Einmánuðr in winter and Heyannir, the haymaking month, in summer, though it is doubtful whether ordinary people used them all. Þorri and Gói are the names with the firmest footing in the sources. Tales of Þorri as a frost god come from a late legendary text. The word Yule is old too: Bede, writing in 725, gives Giuli as the Old English name for December and January.