I'm sure several cities have celebrations similar, or for that same date/reason.
Avanthal -
The Departure and Homecoming of Morwen- Every winter Morwen leaves Avanthal to spread the cold of Winter throughout the rest of Mizahar. At the end of Fall and at the beginning of Spring there are celebrations for Morwen. The entire city is lit up and alive in Morwen's honor. All of the holds participate in making the celebration the best and happiest time for Morwen. Morwen hates to leave the Vantha and the Vantha hate to see her go, so they see The Departure, as it is called, as one last celebration before she departs. The Homecoming is a much bigger and brighter celebration. The Vantha rejoice in the happiness that Morwen will be with them for another three seasons.
Sultros -
The first day of Spring marks the birth of Isengir Izurus Sultros and is known as the Day of the King. This day is filled with celebration and prayer while many Isur dedicate completed works in the name of King Sultros as well as Izurdin. It is considered the holiest of days where in fact all Isurian kings are honored all the way back to King Izurith, mortal son of Izurdin. Prior to the Valterrian, this holiday did not exist
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Wind Reach - I'm sure they probably celebrate the first day as well since they celebrate everything.
The Inarta use any excuse to celebrate holidays.
Kalinor - Here's a maybe, doesn't specify the date.
Swiata vo Viratas, The Festival of Viratas:
In spring, when flowers bloom and green takes over the land above, the Symenestra in their underground city celebrate.
Taloba -
Anniversary of the Valterrian: Carrying over from the last day of winter, this is a day of remembrance. The dead are remembered, and survival celebrated.
Black Rock -
The Day of the Dead is as seasonal festival that celebrates the dead and dying, as well as welcoming the newly dead to the ranks. It occurs each season, usually in the beginning.
Endrykas -
Spring: Feast of Life
Early spring is a particularly spiritual time for the Drykas people, they honor the Gods and Goddesses that continue to bring life to their grassland home. Great displays of light, costume, and generosity are celebrated amongst pavilions alike, with all conflicts aside; the Drykas moto during this time is to 'start anew'. Reimancers, dancers, and performers alike showcase their art on stage in pubs and on outdoor platforms sectioned off with an audience of cushions and tables. The entirity of the Drykas people traveling with Endrykas take this time to renew their personal goals and replenish their spirits, and the theme of courtship and love is emphasized during this time as they follow the rhythm of nature's regeneration of life. It can be expected that during this time, the seeds of love are planted and from them grow blossoms of love and families to carry on the Drykas legends.
The first day is spent setting up the Endrykas encampment; horseclan members scatter themselves around the center of their traditional firepit, which is where the Stalk Meet takes place. From the center out, Drykas pavilians and tents are erected in a sequence of circles over the land as visitors of the city make camp on the outskirts - increasing the overall size of Endrykas by sometimes three times its size. By nightfall before the Drykas consume their meal for the night, everyone takes part in a city wide ceremony of prayer each night, paying their respects to first Semele, Zulrav, and Caiyha, and then each individual personally pays homage to any other Gods and Goddesses they worship.
Riverfall - Maybe this one too.
Day of Revival – This day is celebrated on the coming of the spring rains. Usually before the 15th day of spring, The Akalak take comfort in the fact that winter is finished and the city stirs more than when winter froze everything. The rains indicate crops will grow and the race will survive another year and for this they celebrate Makutsi and pay respects for Bala in order for her to bless the growing season.
Yahebah -
The Great Mourning: Held on the first day of spring, the Great Mourning is a time of reflection and thanks marking the anniversary of the Valterrian. Benshira will walk the walls of Yahebah and mend any damage caused by the previous year. If brick are replaced, they usually bear the names of those who passed in the previous year.
Hope this helps some, I found all of this in the Wiki.