Yom Kippur has a movable date on the Western calendar (January - December) -- this week in 2015

from an online posted article at CHABAD dot-org/


Yom Kippur, the Day of Atonement, falls on the Hebrew calendar date of 10 Tishrei. Here are the coinciding secular dates for upcoming years:
2015:   September 22-23;
2016:   October 11-12;
2017:   September 29-30.


Note: The Jewish calendar date begins at sundown of the night beforehand. Thus, all Yom Kippur observances begin at sundown on the first secular date listed, and conclude the following day at nightfall.