Obviously, October is particularly special because of Samhain (Hallowmas/All Hallows) at the end of the month. It is a period between times. The leaves are changing and the air is crisp and clear as the dark nights begin to draw in.
The veil between the worlds is said to be thinner at this time. Remember those that have gone before you and honour your ancestors.
October lends itself to drama and atmosphere. It is a good excuse to make the most of this time by overloading on the witchy decorations.