The Coligny Calendar is the earliest Celtic 13 month calender.
Samonios meaning Seed-fall
Dumannios meaning The Darkest Depths
Riuros meaning Cold-time
Anagantios meaning Stay-home time
Ogronios meaning Time of ice
Cutios meaning Time of winds
Giamonios meaning Shoots-show
Simivisonios meaning Time of Brightness
Equos meaning Horse-time
Elembiuos meaning Claim time
Edrinios meaning Arbitration
Cantlos Period meaning Song-time
The extra month(intercalary) is mid-Samonios. This would work similar to Jewish or Islamic calendars. In this calendar we are in Dumannios.
However, there is also a very funky tree calendar, which is:
Dec. 24 Jan. 21 I am a stag of seven tines Beith the Birch
Jan. 22 Feb. 18 I am a wide flood on a plain Luis the Rowan
Feb. 19 Mar. 18 I am a wind on the deep waters Nuinn the Ash
Mar. 19 Apr. 15 I am a shining tear of the sun Fearn the Alder
Apr. 16 May 13 I am a hawk on a cliff Saille the Willow
May 14 Jun. 10 I am a fair amongst flowers Huath the Hawthorn
Jun. 11 Jul. 8 I am a god who sets the head afire with smoke Duir the Oak
Jul. 9 Aug. 5 I am a battle-waging spear Teinn the Holly
Aug. 6 Sep. 2 I am a salmon in a pool Coll the Hazel
Sep. 3 Sep. 30 I am a hill of poetry Muinn the Vine
Oct. 1 Oct. 28 I am a ruthless boar Gort the Ivy
Oct. 29 Nov. 25 I am a threatening noise from the sea Ngetal the Reed
Nov. 26 Dec. 22 I am a wave of the sea Ruis the Elder
Dec. 23 Who but I knows the secret of the unhewn dolmen?
And in that calendar we're in Ruis the Elder
Jane
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