Phoenix uses Mountain Standard Time (MST, UTC−7) year-round. Arizona is one of the few US states that does not observe Daylight Saving Time — meaning Phoenix never changes its clocks. It is the fifth most populous city in the United States and the capital of the sunniest state in the nation.
Phoenix keeps the same UTC−7 offset every day of the year. No spring forward, no fall back — and there is a fascinating reason why.
Phoenix and most of Arizona permanently observe MST (UTC−7). There is no summer offset — the clocks never move. This makes Phoenix one of only two major US metro areas (along with Tucson) to use a fixed UTC offset all year.
Arizona opted out of DST in 1968 under the Uniform Time Act, which allowed states to exempt themselves. The rationale was simple: in a desert city where July temperatures regularly exceed 43°C (110°F), extending evening daylight increases air conditioning demand and energy costs — the opposite of the efficiency DST was designed for.
The official IANA time zone name for Phoenix is America/Phoenix. This is a distinct identifier from America/Denver, which covers the Mountain Time Zone states that do observe DST. The difference matters in programming, calendar apps and scheduling systems.
Because Phoenix does not change clocks, its offset relative to other cities shifts twice a year — not because Phoenix moves, but because everyone else does. In winter Phoenix shares UTC−7 with Denver; in summer Phoenix aligns with Los Angeles (PDT), while Denver moves to UTC−6. This creates scheduling surprises for businesses across state lines.
The Navajo Nation, a large tribal reservation that extends across northeastern Arizona, New Mexico and Utah, does observe DST — making it an island of time change within an otherwise static state. Travellers crossing between Arizona and the Navajo Nation must adjust their clocks accordingly.
Phoenix is a fast-growing technology hub. TSMC is building a multi-billion-dollar chip fabrication plant in north Phoenix. Intel has operated major facilities in nearby Chandler for decades. The fixed MST time zone simplifies scheduling for tech firms coordinating with Silicon Valley — the offset difference varies seasonally but is always predictable.
Phoenix is the capital and largest city of Arizona, with approximately 1.6 million residents within city limits and over 5 million in the Greater Phoenix metropolitan area — known locally as the Valley of the Sun. It is the fifth most populous city in the United States, the most populous state capital, and one of the fastest-growing large cities in the country, having added more than half a million residents in the 2010s alone.
The city sits in the Sonoran Desert at an elevation of about 340 metres (1,115 feet), surrounded by mountain ranges including the McDowell Mountains, the White Tank Mountains and the iconic Superstition Mountains to the east. The landscape is defined by saguaro cactus, desert washes and dramatic red-rock terrain — a stark contrast to the dense urban grid spreading across the valley floor.
Phoenix is experiencing a semiconductor and technology boom unlike almost any other US city. Taiwan Semiconductor Manufacturing Company (TSMC) broke ground on a $65 billion chip fabrication campus in north Phoenix in 2021 — one of the largest foreign investments in US history. Intel has expanded its Chandler campus repeatedly, and companies like Microsoft, Amazon, and Google operate major data centres across the metro area, drawn by cheap land, stable geology (no earthquakes), and abundant sunshine for solar power.
The healthcare and biomedical sector is another major pillar of Phoenix's economy. The Mayo Clinic has one of its three US campuses in north Phoenix, the Banner Health system is one of the largest non-profit health systems in the country, and Arizona State University (ASU) — ranked among the most innovative universities in the US — is expanding its biomedical research programs in the heart of the city.
Tourism and outdoor recreation are deeply embedded in Phoenix's identity. South Mountain Park, the largest municipal park in the United States, lies within city limits. Nearby Sedona is world-famous for its red rock formations and vortex sites. The Grand Canyon — one of the Seven Natural Wonders of the World — is approximately 360 km (225 miles) north of Phoenix, and Scottsdale is internationally recognised as a premier golf destination with over 200 courses in the metro area.
1.6 million city / ~5 million metro. The 5th most populous US city and the most populous state capital in the country.
TSMC $65B fab campus, Intel Chandler, Microsoft Azure, Google and Amazon data centres. One of the fastest-growing tech corridors in the US.
~1h behind Los Angeles (in summer, same time), ~2h behind New York, ~9h from London, ~15h from Tokyo. No time change ever in Phoenix.
Hot desert climate (Köppen BWh). World-record heat: 50°C (122°F) reached in July 1990. Over 299 sunny days per year — the sunniest major city in the US.
English and Spanish widely spoken. Also Navajo, Arabic, Vietnamese, Tagalog and Somali across the metro — reflecting both the Southwest's heritage and recent immigration waves.
+1 (US country code). Area codes: 602 (Phoenix), 480 (Scottsdale/Tempe/Mesa), 623 (West Valley). Currency: US Dollar (USD, $).
Because Phoenix never changes its clocks, its offset relative to DST-observing cities shifts seasonally. Times update live every second.
Phoenix & DST — a unique situation: Phoenix stays at UTC−7 all year. When other US cities spring forward in March, Phoenix briefly aligns with Los Angeles (PDT, UTC−7) and is 1 hour ahead of Denver (MDT, UTC−6) — even though both are in the Mountain Time Zone. In November when others fall back, the differences reset. The live clocks above always show the correct real-time difference.
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Phoenix's permanent UTC−7 offset makes it one of the most predictable cities in the US for scheduling — no twice-yearly clock confusion, no missed calls on DST weekends. For TSMC, Intel and other tech companies coordinating between Phoenix and Taipei or Seoul, knowing the offset never changes is a genuine operational advantage.
TimeZoria AI uses your browser's built-in Intl API and the IANA tz database (America/Phoenix) to always display the correct Phoenix time — permanently UTC−7, no exceptions.
Cities connected to Phoenix by technology, desert climate, trade routes and the American Southwest — check their current local time.
Everything you need to know about Phoenix's unique permanent MST time zone, UTC−7 offset and Arizona's DST exemption.