Cultures all over the northern hemisphere that were influenced by Western European colonists recognize the end of October as the period during which the veil between the worlds of the living and the dead is thinnest, but this was never a universal calendrical event. The time of year during which the veil was thinnest varies. Until the 7th century CE, “All Hallow’s Eve” in the U.K. fell on May 13th. Under the influence of colonial Catholocism, directed by Pope Boniface IV, that day changed to November 1st.
The indigenous people of the American Southwest (specifically the Aztec) celebrated feast days for the dead in August. There were actually two days of the dead, “Feast of the Adult Dead Ones” and “Feast of the Little Dead Ones”.
Although cultures throughout the world recognize specific days during which the dead ancestors are celebrated, spirits of loved ones continue to interact with the living on their own schedule and as needed. An example of this is the following ghost story from the Zia Pueblo of New Mexico. An ancestor spirit saved a newborn from the curse of an enemy.