The abbreviation for the US West Coast time zone during standard time is PST, meaning Pacific Standard Time. It represents a UTC offset of minus eight hours, written UTC−8.
The Pacific Time Zone covers Washington, Oregon, California, most of Nevada, and northern Idaho, along with parts of western Mexico. When daylight-saving time is in effect, the abbreviation changes to PDT, or Pacific Daylight Time, and the offset becomes UTC−7.
PST is often confused with MST because the two zones are adjacent and differ by only one hour. CST and EST are farther east and represent Central and Eastern Standard Time. Another subtle point is that “Pacific Time” or PT is the safest year-round label: PST applies only during standard time, while PDT applies during the daylight-saving period. Los Angeles, San Francisco, Seattle, Portland, and Las Vegas are major cities in this zone.