and therefore adjust their clocks one hour ahead during the summer months. Due to the relative population of California， Arizona remains in the Mountain time zone。

as all U.S. states in the Pacific and Mountain time zones except Arizona observe Daylight Saving Time，。

but this is technically inaccurate. While in July it may be the same time in Phoenix as it is in Los Angeles， some people find it easier to comprehend the variation by suggesting that Arizona is "on Pacific (or California) time" during the period of Daylight Saving Time， Arizona is never on Pacific time. Arizona is in the Mountain Time Zone， and (except the Navajo Nation in the northeast corner of the state) does not observe Daylight Saving Time ， observing Mountain Standard Time year-round. ， and therefore does not "spring forward" in April nor "fall back" in October. This results in some confusion。