PST Time Zone: Pacific Standard Time Explained (UTC−8)

What Is PST?

Pacific Standard Time (PST) is UTC−8 — eight hours behind Coordinated Universal Time. It covers the western strip of North America during the non-DST months, roughly early November through mid-March. If you're scheduling a call with someone in California during winter, this is the offset you care about.

The IANA identifier is America/Los_Angeles. Don't use the abbreviation "PST" in code — abbreviations are ambiguous across databases. Stick with the IANA name. Philippine Standard Time also abbreviates to "PST," and I've seen at least two production bugs where a parser picked the wrong one.

PST was formalized in the US through the Standard Time Act of 1918, the same legislation that introduced daylight saving time nationally. Before that, railroads had already been pushing for standardized zones since the 1880s — the mishmash of local solar times was causing scheduling chaos and, more critically, train collisions.

Which States and Cities Use PST?

In the United States, PST applies to:

• California — Los Angeles, San Francisco, San Diego, Sacramento, San Jose
• Washington — Seattle, Tacoma, Spokane
• Oregon (most of the state) — Portland, Eugene, Salem. The exception is a sliver of eastern Oregon around Ontario, which follows Mountain Time.
• Nevada — Las Vegas, Reno, Carson City
• Parts of Idaho — Boise follows Mountain Time, but some northern border communities near Lewiston observe Pacific

British Columbia in Canada (Vancouver, Victoria, Kelowna) also runs on Pacific Time. And Tijuana, Mexico, aligns with Pacific Time due to its economic ties to San Diego — a deliberate choice that makes cross-border commerce and daily commuting far simpler for the hundreds of thousands of people who cross that border regularly.

The Pacific Time zone covers a population of roughly 65 million people in the US alone. Add in British Columbia's 5+ million and you're looking at one of the most economically significant time zones on the planet — Silicon Valley, Hollywood, the Port of Los Angeles, Boeing's headquarters (now technically in Arlington, Virginia, but Seattle still builds the planes), and the West Coast tech corridor from San Diego to Seattle all run on this clock.

PST vs PDT: The Difference That Trips Everyone Up

I've seen this confuse people for years. PST and PDT are not interchangeable. They're two different offsets for the same geographic region.

California actually spends more of the year on PDT than PST — roughly eight months on daylight time versus four on standard. So saying "Pacific Time" (PT) is safer if you're not sure which period you're referring to.

The 2026 transitions: clocks spring forward on Sunday, March 8 at 2:00 AM (jumping to 3:00 AM), and fall back on Sunday, November 1 at 2:00 AM (dropping to 1:00 AM). That "fall back" hour is the one that creates duplicate timestamps in log files and makes event scheduling particularly treacherous — there are literally two instances of 1:30 AM on that night.

The Push for Permanent Daylight Time

California voters passed Proposition 7 in 2018 with 60% support, giving the state legislature the ability to adopt permanent daylight saving time. Washington and Oregon have passed similar bills. The catch? Federal law (the Uniform Time Act of 1966) allows states to opt out of DST entirely — like Arizona and Hawaii do — but it doesn't allow states to make DST permanent without Congress's approval.

The US Senate unanimously passed the Sunshine Protection Act in March 2022, which would have made DST permanent nationwide. It died in the House. As of early 2026, the issue remains in limbo. Several West Coast states are essentially waiting on federal action before they can do anything, despite their legislatures being ready to go.

The permanent-DST camp argues that extra evening light reduces traffic fatalities, boosts retail spending, and aligns better with modern work schedules. Opponents — including sleep researchers and the American Academy of Sleep Medicine — argue that permanent standard time is healthier because it better aligns with our circadian rhythms. The science is pretty clear that the twice-yearly clock change is the worst option, but there's genuine disagreement about which fixed time to pick.

Converting PST to Other Time Zones

Here are the quick math offsets from PST (UTC−8):

These shift when DST kicks in. The gap between California and London, for instance, is 8 hours in winter but only 7 hours for a few weeks in spring because the US and UK switch on different dates. That transition period catches people off guard every year.

The PST-to-India gap is brutal for synchronous work. When it's 9:00 AM in San Francisco, it's 10:30 PM in Mumbai. The only realistic overlap is early morning California time — 7:00 or 8:00 AM — which catches the end of India's workday around 8:30 or 9:30 PM IST. Every tech company with teams in both locations knows this pain.

PST and the Tech Industry

Pacific Time has an outsized influence on global tech because of where the major companies are headquartered. Apple (Cupertino), Google (Mountain View), Meta (Menlo Park), Netflix (Los Gatos), Salesforce (San Francisco), Amazon's consumer division (Seattle) — all PST. When these companies schedule product launches, earnings calls, or developer conferences, the default is Pacific Time.

This creates a knock-on effect. If you're a developer in Berlin and Apple announces a new API at WWDC, the keynote starts at 10:00 AM PDT — which is 7:00 PM CEST. Not terrible. But for engineers in Tokyo, that's 2:00 AM JST. The tech world's gravitational center being on the West Coast means entire workforces in Asia routinely have to adapt their schedules around Pacific Time events.

Stock markets add another layer. The NYSE and NASDAQ open at 9:30 AM Eastern, which is 6:30 AM Pacific. West Coast traders and finance professionals either start very early or accept they're joining the party three hours late. Conversely, the market closes at 1:00 PM Pacific — giving West Coast workers the entire afternoon without the distraction of live trading.

PST in Software: America/Los_Angeles

If you're writing code, always use America/Los_Angeles. The IANA database handles the PST/PDT switch automatically based on the date. A snippet in JavaScript:

new Date().toLocaleString("en-US", { timeZone: "America/Los_Angeles" })

This returns the correct local time regardless of whether PST or PDT is active. Never hardcode a UTC offset — that's a bug waiting to happen.

In Python, it looks like this:

from zoneinfo import ZoneInfo; datetime.now(ZoneInfo("America/Los_Angeles"))

The older pytz library works too, but zoneinfo is built into Python 3.9+ and doesn't carry pytz's quirky localize() requirement. If you're starting a new project, skip pytz entirely.

One gotcha I've hit more than once: database timestamps stored as TIMESTAMP WITHOUT TIME ZONE in PostgreSQL alongside an assumption of "it's Pacific." The moment you deploy a server in a different region — or a team member runs something locally from the East Coast — those timestamps are wrong. Store everything in UTC. Convert to Pacific on display. This advice sounds obvious, but I keep seeing codebases that don't follow it.

The Oregon Split and Other Border Oddities

Oregon is mostly Pacific, but the eastern part around Malheur County (including the city of Ontario) observes Mountain Time. Ontario, Oregon, is essentially a suburb of Boise, Idaho, separated by the Snake River. Its residents work, shop, and socialize in Boise, so following Mountain Time makes practical sense even though the state capital in Salem is on Pacific.

Similar border situations exist elsewhere in the Pacific zone. The Nez Perce Reservation in Idaho follows Pacific Time, while the surrounding area is Mountain. And within Washington state, the entire state is Pacific, but communities near the Idaho border sometimes have informal arrangements with Mountain Time businesses across the state line.

Hawaii Doesn't Use PST

A common misconception: Hawaii is not on Pacific Time. Hawaii Standard Time (HST) is UTC−10, two hours behind PST. Hawaii also doesn't observe DST, so the gap between Hawaii and the West Coast changes seasonally — 2 hours in winter, 3 hours in summer.

Alaska is another one people mix up. Alaska Standard Time (AKST) is UTC−9 — one hour behind PST. Alaska does observe DST, so during summer months it shifts to AKDT (UTC−8), which temporarily puts Anchorage on the same offset as PST. But they're still technically on different named time zones with different IANA identifiers (America/Anchorage vs America/Los_Angeles).

Frequently Asked Questions

Is California always on PST?

No. California is on PST only from early November to mid-March. The rest of the year, it observes Pacific Daylight Time (PDT), which is UTC−7. There have been ballot measures to make PDT permanent, but federal approval hasn't come through yet.

What's the difference between PST and PDT?

PST is UTC−8 (winter), PDT is UTC−7 (summer). The clocks spring forward one hour in March and fall back in November. They're both "Pacific Time" but at different offsets.

How do I convert PST to EST?

Add 3 hours. If it's 9:00 AM PST, it's 12:00 PM EST. This holds when both regions are on standard time. During DST, both shift, so the gap stays at 3 hours year-round.

Does Hawaii use PST?

No. Hawaii uses Hawaii Standard Time (HST), which is UTC−10 — two hours behind PST. Hawaii does not observe daylight saving time.

What time zone is Las Vegas in?

Las Vegas is in the Pacific Time zone. It observes PST (UTC−8) in winter and PDT (UTC−7) in summer. The IANA identifier is America/Los_Angeles.

What is the IANA code for Pacific Time?

The IANA identifier for US Pacific Time is America/Los_Angeles. Use this in software instead of the abbreviation "PST" or "PDT," which are ambiguous across databases.

When does PST switch to PDT?

PST switches to PDT on the second Sunday of March at 2:00 AM, when clocks spring forward one hour. It reverts to PST on the first Sunday of November at 2:00 AM, when clocks fall back.

Sources

• IANA Time Zone Database — America/Los_Angeles entry
• U.S. Department of Transportation — Time Zone Boundaries
• National Institute of Standards and Technology (NIST) — U.S. Time Zones