Arizona doesn’t change its clocks and it wrecks my calendar twice a year

Your colleague in Phoenix has not touched a clock in their life. Their state does not do daylight saving.

And yet twice a year, your meeting with them moves by an hour, and it feels like they did something.

The thing that is genuinely counter-intuitive

A fixed clock is only fixed absolutely. Relative to everyone who moves, it moves.

Arizona sits on Mountain Standard Time permanently. Everyone around it springs forward in March. So:

Same city, same clock, two different relationships to both coasts. Whoever is scheduling has to hold both in their head, and nobody does.

Hawaii is the same story one zone further out, and so are Puerto Rico, Guam and American Samoa.

Why "MST" makes it worse

Phoenix is on MST all year. Denver is on MST in winter and MDT in summer.

So the same three letters describe a fixed clock in one city and a moving one in another. An invite that says "10am MST" is unambiguous for Phoenix and wrong for Denver half the year — and most people reading it will not know which city was meant.

Write "Phoenix." It resolves through the time zone database to America/Phoenix, which encodes the exemption correctly.

What to actually do

Create the recurring event with a zone attached. If the series is anchored to America/Phoenix, it stays put and your side shifts around it correctly. If it is anchored to your zone, Phoenix drifts. Either can be right — pick deliberately, and pick the zone of whoever most needs the time to be stable.

Put both local times in the title:

Sprint review — 09:00 Phoenix / 12:00 New York

Then when it drifts, it is visible at a glance rather than after someone misses it.

Diary the two US dates: 2026-03-08 and 2026-11-01. On each, check anything recurring that involves a non-observing location.

The genuinely hard case: three-way meetings

Phoenix plus one observing US zone plus a European participant is the worst combination available, because you have three different transition behaviours — Phoenix never, the US in March and November, Europe in late March and late October.

There is a stretch each spring where all three are in different relative positions from where they started. If you run a meeting like that, the honest answer is to anchor it to one zone, declare that anchor, and accept that the other two will shift around it.

And the Navajo Nation

For completeness: the Navajo Nation does observe daylight saving and extends into Arizona, and the Hopi Reservation inside it does not. If your counterpart is in north-eastern Arizona, "Arizona doesn't change" may not apply to them.

Related: Does Arizona observe daylight saving time? · Which US states don't observe daylight saving?

Figures on this page are computed from the IANA time zone database. Last generated 2026-08-18.