Converting 10 AM PST to Arizona time depends entirely on the time of year. Because Arizona mostly stays on Mountain Standard Time year-round while the Pacific Time Zone observes Daylight Saving Time, the time difference shifts between one and two hours.
During standard time (November to March), 10 AM PST is 9:00 AM in Arizona. During daylight saving time (March to November), 10 AM PST is 8:00 AM in Arizona because Pacific Time moves forward while Arizona clocks stay put.
Why Arizona Time Zones Cause Confusion
Arizona is famous for bucking the national trend on Daylight Saving Time (DST). While the Uniform Time Act of 1966 mandated that states observing DST spring forward and fall back together, Arizona received an exemption in 1968 due to its extreme summer heat. Lengthening daylight into scorching summer evenings meant later air conditioning loads and more energy use, so state lawmakers kept clocks on standard time.
This decision creates a unique rhythm for remote teams, travelers, and anyone scheduling cross-country meetings. Pacific Standard Time (PST) is UTC-8, and Mountain Standard Time (MST) is UTC-7. However, when the Pacific Zone shifts to Pacific Daylight Time (PDT, which is UTC-7) in the spring, Pacific Time and Arizona Time align temporarily.
The Two Conversion Scenarios
To avoid missing meetings or scheduling calls at awkward hours, you need to know which half of the year you're operating in.
1. Standard Time (November to March)
When Pacific Time is on PST (UTC-8) and Arizona is on MST (UTC-7):
- Arizona is 1 hour behind Pacific Time.
- 10:00 AM PST converts to 9:00 AM in Arizona.
2. Daylight Saving Time (March to November)
When Pacific Time shifts to PDT (UTC-7) and Arizona remains on MST (UTC-7):
- Arizona is 2 hours behind Pacific Time.
- 10:00 AM PST (which is technically 10:00 AM PDT during these months) converts to 8:00 AM in Arizona.
The Navajo Nation Exception
If you're scheduling events with people inside the Navajo Nation in northeastern Arizona, the rules flip. The Navajo Nation does observe Daylight Saving Time to maintain consistent timekeeping across its reservation, which spans into Utah and New Mexico.
- If you call someone in the Navajo Nation at 10 AM Pacific during summer daylight saving time, they are on Mountain Daylight Time (MDT), making it 10:00 AM there as well—the exact same time.
- If you call someone in Phoenix or Tucson at that exact moment, they remain on standard mountain time, making it 9:00 AM in those cities.
Practical Scheduling Tips for Remote Work
Working across these boundaries requires simple habits to prevent missed deadlines.
- Use UTC references: When booking international or cross-time-zone calendar invites, let software handle the conversion, but verify the event creator's local rules. You can check official offsets via Time and Date.
- Double-check transition weeks: The switch to and from daylight saving time happens on different weekends in the US and Europe, creating chaotic transition windows where standard offset rules break for a few days.
- State both times: In email correspondence or Slack messages, always write out both zones. For example: "Let's connect at 10:00 AM PST (9:00 AM Arizona time)."
Frequently Asked Questions
Does Arizona observe Daylight Saving Time anywhere?
Yes. While the vast majority of the state does not change clocks, the Navajo Nation reservation in the northeastern corner of Arizona follows DST.
Is Arizona always on Mountain Standard Time?
Phoenix, Tucson, Mesa, and most of the state stay on Mountain Standard Time (UTC-7) all year. They never shift to Mountain Daylight Time.
What time is it in Phoenix when it is 10 AM in California during summer?
During summer (Daylight Saving Time), California is on PDT (UTC-7) and Phoenix is on MST (UTC-7). That means Phoenix is two hours behind California, making it 8:00 AM in Phoenix when it's 10:00 AM on the West Coast.
How do I check current official offsets?
You can reference the National Institute of Standards and Technology time pages for official US time zone definitions and current atomic clock synchronization.
