Calander

right|300px Most of Faerun uses the Calendar of Harptos, named after the long-dead wizard who invented it. Few bother to refer to Harptos by name, since the calendar is the only calendar they know.
Each year of 365 days is divided into 12 months of 30 days, and each month is divided into three tendays. Five special days fall between the months. These annual holidays mark the seasons or the changing of the seasons. The months of Faerun roughly correspond to the months of the Gregorian calendar.
Month --- Name --- Common Name
1 --- Hammer --- DeepwinterAnnual holiday: Midwinter2 --- Alturiak --- The Claw of Winter3 --- Ches --- The Claw of the Sunsets4 --- Tarsakh --- The Claw of the StormsAnnual holiday: Greengrass5 --- Mirtul --- The Melting6 --- Kythorn --- The Time of Flowers7 --- Flamerule --- SummertideAnnual holiday: Midsummer8 --- Eleasis --- Highsun9 --- Eleint ---The FadingAnnual holiday: Highharvestide10 --- Marpenoth --- Leaffall11 --- Uktar --- The RottingAnnual holiday: The Feast of the Moon12 --- Nightal --- The Drawing Down
Season Festivals
Five times a year the annual holidays are observed as festivals and days of rest in almost every civilized land. Each seasonal festival is celebrated differently, according to the traditions of the land and the particular holiday.
Midwinter:Nobles and monarchs greet the halfway point of winter with a feast day they call the High Festival of Winter. Traditionally it's the best day to make or renew alliances. The common folk enjoy the celebration a bit less--among them it's called Deadwinter Day, noted mainly as the halfway point of winter, with hard times still to come.
Greengrass:The official beginning of spring is a day of peace and rejoicing. Even if snow still covers the ground, clerics, nobles, and wealthy folk make a point of bringing out flowers grown in special rooms within temples and castles. They distribute the flowers among the people, who wear them or cast them upon the ground as bright offerings to the deities whom summon the summer.
Midsummer:Midsummer night is a time of feasting and music and love. Acquaintances turn into dalliances, courtships turn into betrothals, and the deities themselves take a part by ensuring good weather for feasting and frolicking in the woods. Bad weather on this special night is taken as an omen of extremely ill fortune to come.
Highharvestide:This holiday of feasting to celebrate the autumn harvest also marks a time of journeys. Emissaries, pilgrims, adventurers, and everyone else eager to make speed traditionally leave on their journeys the following day--before the worst of the mud clogs the tracks and the rain freezes into snow.
The Feast of the Moon:The Feast of the Moon celebrates ancestors and the honored dead. Stories of the ancestors' exploits mix with the legends of deities until it's hard to tell one from the other.