Jews observe the holiday of Yom Kippur, a 25 hour fast with no food or water and a day of prayer.
Jews in California celebrate Yom Kippur the same way that Jews the world over celebrate Yom Kippur.
Yom Kippur
In 2010, Yom Kippur is celebrated from sunset, September 27 to nightfall, September 28.
The synagogue is the Jewish place of worship, and Yom Kippur is celebrated there.
The Jews celebrate Yom Kippur and Hanukkah.
Jews
Jews don't have churches - they have synagogues, and yes, they go to synagogue during Yom Kippur.
September or October
Yom Kippur
No.
The holiday in question is YOM KIPPUR.