This week we are entering Haustmánuðr, which is the sixth and last summer month according to the old Norse calendar. The old Icelandic calendar states that Haustmánuðr starts on Thursday in the 23rd week of summer (1), which would translate to right before or around mid-September to mid-October in the Julian calendar, and toward the end of September in the Gregorian calendar. Haustmánuðr means "the month of harvest/fall", but I have seen it called by several other descriptive names, such as Garðlagsmánuðr (2) - signifying that it is the time to fix up the fences and walls around the farm.
I occasionally hear of the old names of the months, as some of the celebrations and traditions are still being kept alive in Iceland today, across and regardless of religious beliefs. This may be due to the country using the old calendar alongside the Julian calendar after the Christianization up to year 1200, possibly due to several of the laws being directly linked to its content (3), as well as the peculiar and gradual process of the Christianization of Iceland (4-6). Furthermore, the old names of the months were used much longer in the language, and the Latin names were not adopted into the common tongue until the late 18th century (7).
I would like to write a bit about the Norse calendar, and below I have drawn it up as compared to the modern Gregorian calendar (3), in order to make it easier to visualize.
The old Norse calendar was divided into two seasons, summer and winter. Each season had 6 months, with 30 days each (lunar phases). Summer months were Harpa, Skerpla, Sólmánuðr, Heyannir, Tvímánuðr and Haustmánuðr, and the winter months Gormánuðr, Ýlir, Mǫrsugr, Þorri, Góa and Einmánuðr.
The 12 months of 30 days each account for 360 days. In the middle of summer (between Sólmánuðr og Heyannir) 4 additional days, not belonging to any specific month, were added. At the end of summer however, two of what would have been the first winter nights were counted into the last summer month. Summer months would thus start on a Thursday, and winter months would start on a Saturday. Like today, a year consisted of 52 weeks, and to make up for the divergence with the solar year, an additional week was added at the end of summer every 7th year (4), called sumarauki, literally meaning "summer addition". In Landnámabók (The Book of Settlements) we can read that "Hallsteinn átti Ósku, dóttur Þorsteins rauðs. Þeira sonr var Þorsteinn surtr, er fann sumarauka", roughly translated to "Hallsteinn had Ósk, daughter of Þorstein the red. Their son was Þorsteinn surtr, who invented the summer addition" (8).
Although seemingly complicated at first glance, I do not find the old Norse system to be particularly more so than the Julian or Gregorian systems, where names of months were changed according to the deeds and victories of emperors, and with length varying between 28-31 days, leap-years and so forth...
It is however deemed unlikely that the days in the old Norse calendar were counted very accurately, especially in the northernmost areas where the sun barely sets during the mid-summer months. Time was counted in weeks of (or weeks left of) summer or winter rather than with numbered days, and years were not counted by an absolute chronology (3). Each of the two seasons was called a "misseri", and the calendar was thus a misseristal (counting of misseris) (9). There are to my knowledge no known accounts of specific "New Years celebrations" in the Viking Age, but the new year is believed to have commenced with the first summer month (10). This is mainly based on the fact that ones lifetime was measured in the number of winters lived, an expression still used in some contexts today (for example, the age of livestock is stated in the number of winters the animal has lived through). The first day of summer was a festive day, and remains a public holiday in Iceland, falling on the first day of Harpa (first Thursday after April 18th).
