Permanent Daylight Saving Time and the Mountain Time Zone

What the Sunshine Protection Act actually changes

A US Senate vote in March 2022 put the bill on the map. It passed by unanimous consent, then died in the House. It has been reintroduced in multiple sessions since, but as of 2026 it has not passed both chambers.

The bill would make daylight saving time the permanent, year-round clock for every state that currently observes DST. States that already opt out, Arizona and Hawaii, would stay on permanent standard time. Time zone boundaries do not move. The rules inside them do.

Permanent daylight saving Mountain Time: what winter would look like

If the bill became law, the Mountain Time Zone would lock onto Mountain Daylight Time. UTC−6. The same offset Denver, Calgary, and Ciudad Juárez use from March to November today.

No spring forward. No fall back. Clocks would read the same number in January as in July.

Summer would look identical to now. Winter would not. Phoenix sunrise on the December solstice is 07:28, sunset 17:24. That is the baseline for the southern edge of the zone. Further north, mornings would stay dark past 08:00. The trade-off is an extra hour of evening light in the coldest months. Supporters call that the win. Critics point to children walking to school in darkness and early shift workers starting long before dawn.

Can Mountain states adopt permanent DST without Congress?

No. That is the legal wall. The Uniform Time Act of 1966 lets states exempt themselves from DST entirely. Arizona and Hawaii did exactly that. Permanent standard time is legal right now.

Permanent DST is not. If a state observes DST at all, it must follow the federal schedule. The only way to lock onto DST year-round is for Congress to change the federal schedule. The Sunshine Protection Act would do that. Until it passes, every state bill pushing for permanent DST is a placeholder.

This asymmetry shapes every state-level debate. Legislators can vote to stop the clock changes, but only by choosing standard time, which means darker summer evenings. Most voters want brighter evenings. So the bills push for permanent DST, and every one of them includes a clause that says the change takes effect only after Congress authorises it.

Which Mountain states have tried to lock the clock?

Colorado, Utah, Wyoming, and Montana have all introduced bills to adopt a single year-round time. None can take effect without federal action.

Colorado's bill passed one chamber in 2023 and stalled. Utah's died in committee. Wyoming and Montana saw similar proposals introduced and shelved. The pattern is consistent: public appetite for ending the twice-yearly switch runs ahead of the legal machinery to permit it.

Alberta's 2021 referendum on year-round daylight time

Alberta put the question to voters in 2021. Should the province adopt permanent daylight saving time? The result: 50.2 percent voted no. Narrow. Decisive enough to keep Alberta on the standard Mountain schedule: MST in winter, MDT in summer.

British Columbia passed legislation to move to permanent DST but tied it to action from Washington, Oregon, and California. Those states have not moved. BC's law sits idle.

Arizona already has permanent Mountain Time. It is just standard.

Arizona exempted itself from DST in 1968. The reason is heat. Extra evening daylight in summer pushes air conditioning loads higher, not lower. The state stays on Mountain Standard Time, UTC−7, all year.

In summer, Phoenix clocks match Los Angeles. But Arizona is not on Pacific Time. It is on permanent MST. In winter, it aligns with the rest of the Mountain zone.

The Sunshine Protection Act would not force Arizona to change. The bill explicitly lets current DST-exempt states remain on permanent standard time. Arizona would stay exactly where it is.

The Navajo Nation complicates the picture. It covers parts of Arizona, Utah, and New Mexico and does observe DST. The Hopi Reservation, surrounded by the Navajo Nation, does not. The result is a DST doughnut inside Arizona's borders.

When does Mountain Time change clocks in 2026?

Clocks spring forward on Sunday 8 March 2026 at 02:00 local. MST (UTC−7) becomes MDT (UTC−6). They fall back on Sunday 1 November 2026 at 02:00 local. MDT returns to MST.

The 2027 spring forward is Sunday 14 March. The 2027 fall back is Sunday 7 November.

Could a Mountain state choose permanent standard time instead?

Yes. That path is open. Arizona took it. Any Mountain state can pass a law exempting itself from DST and stay on MST year-round. Most have not, because permanent standard time means earlier sunsets in summer. Voters tend to dislike that trade.

Is Ciudad Juárez on Mountain Time?

Yes. Ciudad Juárez uses the IANA zone America/Ciudad_Juarez. It follows Mountain Time rules, including DST, to stay aligned with El Paso, Texas, across the border.

What time zone does Phoenix use year-round?

Mountain Standard Time. UTC−7. It does not observe DST. In summer, Phoenix clocks read the same as Los Angeles, but Phoenix is not on Pacific Time.

If I schedule a meeting with someone in Denver in July, what time zone do I use?

Denver in July is on Mountain Daylight Time, UTC−6. Phoenix in July is on MST, UTC−7, one hour behind Denver. Always confirm whether the person is in a DST-observing part of the zone.