闰 December : 闰 December is also called 闰 Lunar month. If there are two Decembers in the lunar year, the first month is called "December (Lunar month)" and the second December is called "闰 December (闰月 月)". 闰 December is the rarest of all 闰 months. There has been no 闰 December from the 17th century to the 33rd century, and there have been no 闰 December in the 36th ~ 38th century, 41st ~ 47th century, and 49th century. The last 闰 December appeared in the 16th century in 1574, and the next 闰 December appeared in the 34th century in 3358. The year following December is the latest year of the Spring Festival, because the date of the Spring Festival in December is generally January 31 or February 1.