America/Phoenix time zone
5:54AMMST
MSTUTC−7−2 h vs New York (you)
No transitions: America/Phoenix stays on MST (UTC−7).
About America/Phoenix
America/Phoenix is the IANA time zone for MST: AZ (most areas), Creston BC in United States and Canada. It currently keeps Mountain Standard Time (MST, UTC−7) all year.
The zone serves 2 countries or territories because their clocks have agreed since 1970; tzdata lists them together in zone1970.tab. That says nothing about borders or sovereignty, as the file’s header points out.
Its principal location is Phoenix at 33.45° N, 112.07° W.
Abbreviations in use: MST. Offset page: UTC−7.
Rule for future years (POSIX TZ string)
MST7
The standard time is called MST and is UTC−7. POSIX writes the offset with the opposite sign (west of Greenwich is positive), which is why the string says "7". There is no daylight saving rule: the zone stays on this offset for every year after the end of its explicit transitions. Software that has no full tzdata copy, such as many embedded devices, can use this string directly as the TZ environment variable.
History of America/Phoenix since 1970
The record starts with local mean time (UTC−7:28), which ended on November 18, 1883. The first daylight saving time in the record is in 1918.
| Years | Clocks | Abbreviations |
|---|---|---|
| 1970 onward | UTC−7 all year | MST |
Before 1970
11 offset changes before 1970 in the record:
- Sunday, November 18, 1883: UTC−7:28 → UTC−7 (MST)
- Sunday, March 31, 1918: UTC−7 → UTC−6 (MDT), daylight saving time
- Sunday, October 27, 1918: UTC−6 → UTC−7 (MST)
- Sunday, March 30, 1919: UTC−7 → UTC−6 (MDT), daylight saving time
- Sunday, October 26, 1919: UTC−6 → UTC−7 (MST)
- Monday, February 9, 1942: UTC−7 → UTC−6 (MWT), daylight saving time
- Saturday, January 1, 1944: UTC−6 → UTC−7 (MST)
- Saturday, April 1, 1944: UTC−7 → UTC−6 (MWT), daylight saving time
- Sunday, October 1, 1944: UTC−6 → UTC−7 (MST)
- Sunday, April 30, 1967: UTC−7 → UTC−6 (MDT), daylight saving time
- Sunday, October 29, 1967: UTC−6 → UTC−7 (MST)
tzdata commits to accuracy from 1970 for every zone (zone1970.tab); earlier entries are historical research and may be incomplete.
Aliases and zones with the same clock
These older or country-specific IDs are links to America/Phoenix in tzdata. Their pages redirect here: America/Creston, MST, US/Arizona.
Other zones that keep exactly the same time under the current rules (but have a different history): America/Dawson, America/Dawson_Creek, America/Fort_Nelson, America/Hermosillo, America/Mazatlan, America/Vancouver, America/Whitehorse.
Places on America/Phoenix
Convert Phoenix time
Using America/Phoenix in code
Every major platform reads the same IANA ID. Store instants in UTC and convert with the ID at display time; never store a fixed offset for a place that has daylight saving time.
// JavaScript
new Date().toLocaleString('en-US', { timeZone: 'America/Phoenix' })
# Python 3.9+
from zoneinfo import ZoneInfo
from datetime import datetime
datetime.now(ZoneInfo('America/Phoenix'))
// Java
java.time.ZonedDateTime.now(java.time.ZoneId.of("America/Phoenix"))
// Go
loc, _ := time.LoadLocation("America/Phoenix")
time.Now().In(loc)
-- PostgreSQL
SELECT now() AT TIME ZONE 'America/Phoenix';
# Shell
TZ='America/Phoenix' datePlatforms ship their own copy of tzdata and update it on their own schedule. After a rule change, outputs can differ until the platform updates; this page uses tzdata 2026f.