The calendar is split into 12 months, each lasting 3 tendays, or 30 days. There is an additional 5 days between certain months; Midwinter, Greengrass, Midsummer, Highharvestide, and Moonfest. Bringing the total number of days up to 365 days per year.
Link to Fantasy Calendar
No widespread holidays.
Midwinter: Was a festival to mark the midpoint of winter. It occurs on the day between Hammer and Alturiak. The nobles refer to the day as Midwinter and use it as a time to renew alliances. The common people refer to the holiday as Dead Winter Day, a reference to the cold and hard times still remaining.
Alturiak 10: Night of Lights. During the Night of Lights, the normally bleak night sky is replaced by a countrywide aurora, lasting all throughout the night.
Ches 15: Day of Harpsong. Signals the end of winter and the beginning of warmer weather. Celebrated mostly by bards and musicians. The day is mostly for playing, singing, and drinking.
Ches 19: Spring Equinox. Marks the first day of spring and the day of crossing. The crossing is the time of year when portals to the Feywild open wider, allowing for animals and people to walk freely between them. Without using planar travel, this is the only way for people to cross to the Feywild and back. In some locations, it is common for the villagers to have parties with the fey creatures, like pixies and satyrs.
Tarsakh 4: Festival of the Storms. Celebrated mostly in the hopes for boosting crop production. It's said that the amount of rain that falls that day is an indication of how much is to come the rest of the year. Celebrated by mostly farmers, and worshipers of Talos.
Greengrass: Was a festival to mark the middle of spring. It occurred on the day between Tarsakh and Mirtul. Traditionally, the wealthier people brought out flowers to give to the less wealthy, who either wore them or spread them on the ground to encourage the deities to usher in the summer.
Mirtul 26: Fest of Youth. Celebrated by the youth of Faerun. A day for children to be excused from chores and for the upper class, a day to give gifts to children that have been good that year.
Kythorn 18: Festival of Petals. A time that most people choose to spiffy up their town with flowers and plants. Also to clean out their homes of garbage. Its celebrated by pretty much everyone, as it's not really a time for feasting or partying, but just enjoying beauty.
Kythorn 20: Summer Solstice. Marks the first day of summer and is the longest day of the year. Northern cities get around 16 hours of sunlight. Celebrated by followers of Amaunator.
Flamerule 4: Hero’s Day. Hero's day is celebrated mostly by adventurers. It's a time for tavern brawls, drinking, and honoring fallen friends. It's usually only celebrated at night in taverns and places that offer free drinks for adventurers.
Midsummer: Was a festival that celebrated love and music through feast. It occurred on the day between Flamerule and Eleasis. It was a time when love advanced, and it was said the deities themselves took a hand to ensure good weather. If bad weather was experienced on this night it was considered an extremely bad omen. Shieldmeet occurred the day after Midsummer on leap years.
Eleasis 12: Parents Feast. Celebrated by the parents of Faerun. Kids are to work extra hard today, and make sure they let their parents know how much they appreciate them. Celebrated mostly as a joke between parents, but some elven families take it very seriously.
Eleint 21: Autumn Equinox. Marks the first day of Autumn and the convergence. The Convergence is the time of year when the portals to the shadowfell open for creatures and people to travel back and forth. Many people choose to dress up in costumes of monsters to trick creatures from the shadowfell, however most know that this would do little to deter them. The moon on this day also turns a bloodshot red color.
Highharvesttide: Was a festival that takes place on the day between Eleint and Marpenoth. It was traditionally a feast to celebrate the harvest and the abundance of food, but also the time when those wishing to travel left on their journeys before winter set in. Traditions varied from community to community, but examples of festive activity included food-related contests; races and challenges of skill and strength; receiving homemade sweets from the local clergy; and priests blessing larders, wine cellars, grain bins, and food preserves. This day was often an important anniversary to various governments. Often, taxes and tithes came due, rulers held "open courts" to hear the concerns of their citizens, oaths were publicly renewed, troops received marching orders to new duty stations, and guilds met to confer on prices and rate changes for goods and services.
Marpenoth 29: Craftsman Fest. A day of appreciation for all the craftsmen across Faerun. From blacksmiths to woodworkers, all members of the craft are given a day off and some much needed rest. However, most craftsmen see this as an opportunity to get ahead, and most will offer a discount on prices and labor just for the day.
No widespread holidays.
Moonfest: Also known as feast of the moon, is a festival that occurs on the day between Uktar and Nightal. It was the last great festival of the calendar year. The day traditionally marked the onset of winter. It was also a time to celebrate and honor the ancestors and the respected dead. On this day, folk blessed their ancestors' graves and performed the Ritual of Remembrance. This was a time to hear of past heroes, great treasures, and lost cities. Priests of a number of deities of various pantheons held rites, ceremonies, and festivals on the Feast of the Moon. Many, though not all, focused on remembering the dead in one way or another.
Nightal 20: Winter Solstice. Marks the first day of winter and is the darkest day of the year. Northern cities sometimes can get 18 hours of darkness. Not celebrated outside of a few worshipers of Auril.