What time zone is Arizona in?

Arizona is on Mountain Standard Time (MST), UTC−7, all year round — and it does not observe daylight saving time. That means for roughly eight months of the year Arizona matches Pacific time, and for the other four it matches Mountain.

— right now in Arizona
Same as — today

The one exception is the Navajo Nation in the north-east corner, which does change its clocks. More on that below.

Arizona against the rest of the country

Arizona never moves, so everyone else moves around it. The same state is one hour from California in winter and zero hours from it in summer.

When it's noon in ArizonaSummer (Mar–Nov)Winter (Nov–Mar)
Los Angeles12:00 — same11:00 — 1 hr behind
Denver1:00 pm — 1 hr ahead12:00 — same
Dallas / Chicago2:00 pm — 2 hrs ahead1:00 pm — 1 hr ahead
New York / Atlanta3:00 pm — 3 hrs ahead2:00 pm — 2 hrs ahead
Anchorage11:00 — 1 hr behind10:00 — 2 hrs behind
Honolulu9:00 — 3 hrs behind9:00 — 3 hrs behind

Is Arizona MST or MDT?

Always MST. Because the clocks never change, Arizona is never on Mountain Daylight Time. If a booking system, a rate confirmation or a phone shows you "Arizona, MDT" in July, it is wrong — and it is wrong by a whole hour, which is exactly the kind of error that turns an 8am appointment into a missed one.

Why doesn't Arizona change its clocks?

Arizona did observe daylight saving in 1967, the first year the Uniform Time Act made it standard. It opted out permanently the following year and has stayed out since.

The reason is heat. Daylight saving moves an hour of daylight into the evening, and in a place where a June afternoon runs past 110°F, that is an extra hour of sun on the house and an extra hour of air conditioning. Arizona would rather have the sun set earlier. Hawaii, for a different reason — it is close enough to the equator that day length barely moves — made the same choice.

The Navajo Nation exception

The Navajo Nation, in Arizona's north-eastern corner, does observe daylight saving. The reservation also covers parts of Utah and New Mexico, both of which change their clocks, so it keeps one time across all three rather than splitting itself in half every spring.

Inside the Navajo Nation sits the Hopi Reservation, which does not observe daylight saving — it follows the rest of Arizona. So in summer, crossing that corner on US-160 or US-191 can change the time on your phone more than once inside an hour, in both directions.

If you're dispatching a load into Phoenix: a driver working from Dallas in July is three time zones' worth of arithmetic away from a two-hour difference, not one. An 0800 Phoenix appointment is 0600 in Dallas. Book it wrong and the truck sits until the next day's window.

Common questions

What time zone is Arizona in?
Arizona is on Mountain Standard Time, UTC−7, for the whole year. It is the only state on the mainland apart from Hawaii that does not observe daylight saving time, so it stays on MST in summer while the rest of the Mountain zone moves to MDT.
Is Arizona MST or MDT?
Always MST. Because Arizona does not change its clocks, it is never on Mountain Daylight Time. Software and phones that show Arizona as MDT in summer are wrong.
Does Arizona observe daylight saving time?
No. Arizona tried daylight saving in 1967 and opted out permanently in 1968 under the Uniform Time Act. In a state where summer afternoons run past 110 degrees, an extra hour of evening sun means an extra hour of air conditioning, so the state chose not to take it.
Is Arizona the same time as California?
For about eight months of the year, yes. From the second Sunday in March to the first Sunday in November, California is on Pacific Daylight Time (UTC−7), which matches Arizona exactly. In winter California falls back to UTC−8 and Arizona is then an hour ahead.
Does the Navajo Nation observe daylight saving time?
Yes. The Navajo Nation in north-eastern Arizona does observe daylight saving, because the reservation also covers parts of Utah and New Mexico and keeps one clock across all three. The Hopi Reservation, which sits entirely inside the Navajo Nation, does not. Driving across that corner in summer, the time can change more than once in an hour.
What time zone is Phoenix in?
Phoenix is on Mountain Standard Time, UTC−7, all year, the same as the rest of Arizona outside the Navajo Nation. Tucson, Flagstaff, Yuma, Mesa and Scottsdale are all the same.

Running a load into Arizona?

The calculator shows the local time at both ends of your lane, where the route changes zone, and your arrival in the receiver's clock — free, no signup.

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