Many northern Gorean cities AR included celebrate the New Year. Typically on this day doors are painted green and a city wide festival is held, staring on the Vernal equinox (March 21) lasting two hands (ten days). Every fourth year the New Year is celebrated on the estra day which occurs between the waiting hand and the day of the equinox.
Assassin of Gor pg 78

Turia and certain other southern regions celebrate their own new year. It is celebrated on the Summer Solstice (June 21). It lasts for ten days like the northern cities.
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The day of the Winter Solstice (December 21)is the First day of the New Year for the wagon people.

The Gorean equivalent of the World's Fair on Earth, these are four huge trade fairs which are held quarterly in the shadow of the Sardar Mountain Range. Each young person of Gor is expected to make a pilgrimage to the foot of the Sardar Mountains before he or she reaches their 25th birthday. They typically last ten full days (plus at least that long for set up and break down) and are scheduled to coincide with the solstices and equinoxes. Therefore, the four annual Fairs are:

The fair of En'Kara (March 21-30)
The fair of En'var (June 19-28)
The fair of Se'Kara (September 22-October 1)
The fair of Se'Var (December 21-30)

Nomads of Gor pgs 116-117, Outlaw of Gor pg 179, Priest Kings of Gor pg 12

Celebrated by most Gorean cities early during the growing season, and believed to ensure a plentiful harvest in the year ahead. Numerous rituals are performed during these three days(April 16-18). Members of the Initiates,and each of the other high castes so their own part during the three days, most of the rituals consist of scarfices or prayers to the Priest Kings in the presence of the homestone. On the last day the homestone is placed usually atop the highest cylinder and sprinkled with sa-tarna grain and ka-la-na wine by Ubar, Administrator or a member of the ruling family.
Tarnsman of Gor pg 68

This day marks the beginning of the Season of Little Grass. This is when the wagon people begin their long journey back from their winter pastures. It is the last day of the second hand of En'Kara(March 30)

Wagon people and the warriors of Turia compete against each other on the plain of stakes during the Second passage hand (may 15-29), they participate in various challenges and ceremonial combats in exchange of Freewomen for slaves.
Nomads of Gor pgs 11-12, 115 & 334

Every tenth year, dating from 10,119 CA (1969 AD), is considered by the Wagon Peoples to be an "Omen Year." Therefore, in 10,129 CA (1979 AD) and in 10,139 CA (1989 AD), the Wagon Peoples halted their annual trek past Turia and various Omens were divined by their haruspexes regarding the future of the tribes and the safety of the bosk. This ceremony typically occurs in late spring, sometime during the month of Camerius. The next such Omen Year will be 10,149 CA (1999 AD).

The Festival of Slaves", it is held in most Gorean cities (except Port Kar, where it is not celebrated at all) on the last day of the Twelfth Passage Hand (March 15th). In Ar, it is celebrated on the last day of the fifth month (August 12th), the day which precedes the Love Feast. Upon this day,
slaves may take liberties which are otherwise not permitted them during the year, including the drinking of wine and liquor, the freedom to roam at will (provided of course they do not attempt to escape from their owners permanently), the freedom to choose their own sexual partners and to couch
with slaves of the opposite sex whom they find attractive, temporary suspension of all work and duties, and even the opportunity to play (minor) tricks and practical jokes upon freepersons. After the twentieth ahn, however, they are expected to be back in their respective kennels and slave
quarters to resume the services required by their imbonded status; slaves who "go renegade" during Kajuralia are typically punished severely if recaptured, and are often executed for such an offense.

Five day celebration within Ar, held during [Slave Auction] the Fifth Passage Hand (August 13th-17th). It is a time wherein many slaves are sold; the fourth day of the Love Feast (August 16th) is typically considered the climax of the festival in regard to the sale of slaves. The fifth day
(August 17th) is normally reserved for great contests and spectacles in the Stadium of Blades, grand races in the Stadium of Tarns, great Kaissa championships and general celebratory feasting.

This is when the bosk herds of the wagon people pass closest to Turia on or around the second hand of Se'Kara (September 22-26).

Held in Port Kar to celebrate their great naval victory over the combined fleets of Cos and Tyros (October 11).

This is a Festival celebrated in some Gorean cities on the last day of the Third Hand of the eighth Gorean month (October 31st). It is similar in many respects to the southern Festival known as Carnival, except it lasts only for the period of one night. Also known as the "Festival of the Cities of Dust," in homage to the spirits of the deceased who died during the last year.

this is an annual celebration held in Torvaldsland. During this three to five day period sheildmen of the various Jarls travel to the hall of their leader and submit their weaponary for inspection, and formally repledge their oaths of loyalty. This celebration is usually held during the middle of the ninth month and varies according to the weather and current political situations.

During the middle of the ninth month through the second hand of En'Kara, the wagon peoples typically occupy their winter pastures.

New Year (Wagon Peoples)
The day of the Winter Solstice (December 21st) is celebrated by the Wagon Peoples as the first day of the new year, and marks the beginning of The Season of Snows. In addition, the women of the Wagon Peoples keep a calendar of their own, based upon the phases of the largest of the three Gorean moons. It consists of fifteen separate divisions, each named after one of the fifteen diiferent kinds of bosk, for instance: "The Moon of the Brown Bosk", "The Moon of the Spotted Bosk", etc.

Held in many southern cities, most notably Port Kar. During this celebration it is often customary to garb oneself in outlandish costumes or masks and attend various masquerade fetes and feasts. This is held during the five days of the twelfth passage hand(March 11-15).

During this hand doors are painted white, little food is eaten. There is little drunk and there is no singing or public rejoicing in the city. Walls and doors are adorned with sprigs and branches from the brak bush to ward off ill-lick in the coming year. On the day of the Vernal euinox the Ubar or Adminsitrator of the city performs a ritual,or greeting of the sun, after which doors are repainted and the brak bush is removed. (March 16-20).
Assassin of Gor pg 211