UTC to PST/PDT Conversion Is Not Always Minus 8 Hours

If someone tells you to subtract 8 hours from UTC to get Pacific Time, they are right for about 4.5 months of the year and wrong for the other 7.5 months. Pacific Standard Time (PST) is UTC-8. Pacific Daylight Time (PDT) is UTC-7. If you use UTC-8 during the summer, every converted time will be one hour off. This is not a minor inconvenience. A meeting scheduled at "9 AM Pacific" means 17:00 UTC during PST (November through March) and 16:00 UTC during PDT (March through November). If your code hardcodes UTC-8, every summer meeting is scheduled an hour early. The transition dates In the US, Daylight Saving Time begins on the second Sunday of March at 2:00 AM local time and ends on the first Sunday of November at 2:00 AM local time. These dates were set by the Energy Policy Act of 2005 and took effect in 2007. In 2026: PDT starts: March 8, 2026, at 2:00 AM (clocks spring forward to 3:00 AM) PST starts: November 1, 2026, at 2:00 AM (clocks fall back to 1:00 AM) From March 8 to November 1: