Arizona Time Zone: Same as California in Summer, Denver in Winter

Last updated October 26, 2026 · Written by Han with AI assistance, fact-checked against official sources.

Arizona sits in the Mountain time zone but keeps standard time all year, while its neighbors move their clocks. That is why the time difference to California and Colorado depends on the date.

Compare Phoenix, Los Angeles and Denver on any date in the Meeting Planner.

9 a.m. in Phoenix through the year

Phoenix never changes its clock, so every shift in this table comes from the other city. Bold cells are the ones that moved since the row above. The times are calculated from the time zone database for 2026.

Two US dates matter for calls inside the country. After the spring change, Phoenix is one hour behind Denver, two behind Chicago and three behind New York. After the autumn change, Phoenix and Denver match and Los Angeles is an hour behind. The next change is on Sunday, November 1, 2026, when the rest of the US clocks fall back. London moves on its own dates in late March and late October, so the gap to Phoenix is 7 hours in the UK winter and 8 hours in the UK summer.

Why Arizona skips daylight saving time

Federal law, 15 U.S.C. 260a, sets daylight saving time from the second Sunday in March to the first Sunday in November. It also lets a state that lies entirely in one time zone exempt itself by law. Arizona did that. Its statute, A.R.S. 1-242, sets the state's standard time at the 105th meridian west and rejects daylight saving time. Hawaii is the only other state that does not change its clocks.

Arizona did change its clocks for a while. The time zone database shows Phoenix moving forward in 1918 and 1919, during parts of the Second World War, and once more from April 30 to October 29, 1967. The Pima County Public Library notes that 1967 was the first summer of daylight saving time in Arizona since the war, and that the legislature rejected it in 1968. Phoenix has stayed on UTC−7 since.

The Navajo Nation and the Hopi Reservation

NIST lists Arizona among the places without daylight saving time, "with the exception of the Navajo Indian Reservation, which does observe DST." The Navajo Nation reaches into New Mexico and Utah, which both change their clocks, so in summer the reservation keeps the same time across all three states. The Hopi Reservation lies inside the Navajo Nation and follows the rest of Arizona.

This means a drive between Tuba City and Moenkopi, or across the Hopi mesas, can change the clock by an hour between March and November. In winter the whole state shows the same time. In the time zone database, the Navajo Nation uses America/Denver and the rest of Arizona uses America/Phoenix.

Arizona and "Mountain Time"

Arizona is in the Mountain time zone, but in summer it is not on Mountain Daylight Time. A call set for "10 a.m. Mountain" in July means 10 a.m. in Denver and 9 a.m. in Phoenix. In winter the two are the same.

When you set a time zone in a calendar app, pick Phoenix or the Arizona entry, not Mountain Time, for anyone in Arizona outside the Navajo Nation. For Window Rock or Kayenta, use Denver.

Planning calls with Arizona

• Write the city in the invite: "10 a.m. Phoenix time" is clear all year, while "MST" and "Mountain" mean different clocks in summer.
• A weekly call set in Phoenix moves for everyone else twice a year. A 9 a.m. Phoenix stand-up is at 11 a.m. in New York in winter and noon in summer.
• If your team spans Los Angeles and Phoenix, they share all eight office hours in summer and seven in winter.

Open the Meeting Planner to test a time, or see the city pages for Phoenix, Los Angeles and Denver. Which US States Have Two Time Zones? covers the states that are split by a zone line, and the US time zones guide covers all six zones.