Phoenix time zone history
The Phoenix zone has kept UTC−7 since 1883, with no clock changes since 1970, tied second-longest run among the 148 zones with no change of standard time since 1970. Phoenix left local mean time (UTC−7:28:18) in 1883, tied for the earliest switch among the 11 zones on UTC−7 standard time with local mean time in the record.
UTC−7
Standard time is UTC−7 (MST) all year under the current rules.
UTC−7 every day since 1970
Before 1970
Standard time changes
| Date | Change | New standard time | Clock label |
|---|---|---|---|
| Before 1970 | |||
| November 18, 1883 | Local mean time (UTC−7:28:18) replaced | UTC−7 | MST |
Daylight saving periods
| Years | Clocks go forward | Clocks go back | Shift and labels |
|---|---|---|---|
| 1918–1919 | last Sunday in March, 02:00 | last Sunday in October, 02:00 | 1 hour, MST to MDT |
| 1942 | February 9 | not that year | 1 hour, MST to MWT |
| 1944 | April 1 | January 1, October 1 | 1 hour, MST to MWT |
| 1967 | April 30 | October 29 | 1 hour, MST to MDT |
Also on UTC−7
Hermosillo (Mexico), Ciudad Juárez (Mexico), Denver (United States), Boise (United States), Mazatlan (Mexico), Vancouver (Canada), Dawson Creek (Canada), Fort Nelson (Canada), Whitehorse (Canada) and Dawson (Canada) (nearest first; 1 more on the list of offsets).
Clocks next door since 1970
- Tijuana (Mexico) (472 km): same time except 8,711 days in 1970–2026; 1 hour behind today.
- Hermosillo (Mexico) (498 km): same time except 609 days in 1996–1998.
- Ciudad Juárez (Mexico) (557 km): usually 1 hour ahead; different on 4,413 days in 1996–2026; same time today.
- Los Angeles (574 km): same time except 8,613 days in 1970–2026; 1 hour behind today.
- Chihuahua (Mexico) (782 km): usually 1 hour ahead; different on 4,264 days in 1996–2022.
How it compares
On standard time, clocks in Phoenix run 28 minutes ahead of local mean solar time.