What time zone is Yokohama in?
Yokohama sits inside Japan Standard Time. The offset is UTC+9, fixed every day of the year. No spring forward, no fall back. The time you see in Yokohama right now is the same time you will see in December, July, or any other month.
JST means UTC+9, always
Japan Standard Time runs nine hours ahead of Greenwich. When it is noon in Yokohama, it is 03:00 in London in January and 04:00 in July. New York is 14 hours behind in January, 13 hours behind in July. The offset never wavers.
The abbreviation JST causes trouble. Some sources use JST for Jerusalem Standard Time, which is UTC+2. That is a seven-hour gap from Yokohama. If a schedule says JST, confirm the offset. For Yokohama, JST means UTC+9 every time.
Why Japan uses one clock for 3,000 kilometres
Japan stretches roughly 3,000 kilometres from Hokkaido to Okinawa. Every city, Sapporo, Naha, Yokohama, shares the same hour. A country that wide could split into two or three zones. It does not.
The Meiji government unified the time in 1888. A single reference simplified railways, telegraphs, and port operations. Yokohama, opened as a treaty port in 1859, needed a fixed reference for international shipping schedules. The decision held.
The 135°E meridian misses Yokohama
Japan Standard Time follows the local mean time of the 135° east meridian. That line runs through Akashi, in Hyogo Prefecture. It does not run through Yokohama. Yokohama sits at 139.65° east, roughly 4.5 degrees further east.
That gap shifts solar noon. The sun peaks over Yokohama at about 11:42 JST, not 12:00. The clock runs ahead of the sun. This is normal for the eastern edge of a time zone.
The effect shows up in daylight. On 21 June 2026, the sun rises at 04:26 and sets at 18:59, giving 14 hours 33 minutes of daylight. On 21 December 2026, sunrise is 06:46 and sunset 16:32. Just 9 hours 46 minutes of light.
Asia/Tokyo is the IANA zone for Yokohama
Computers, servers, and scheduling tools use the IANA Time Zone Database. For Yokohama, the identifier is Asia/Tokyo. No separate zone exists for Yokohama, Osaka, or any other Japanese city. One zone covers the entire country.
Set your calendar, scheduling software, or server to Asia/Tokyo. It holds the full history of Japan's time rules, including the brief DST period. The database records Japan as consistently UTC+9 since 1952, with no transitions since.
Japan adopted a single time in 1888
Before 1888, each city ran on local solar time. Yokohama's port and town hall used the sun. Noon in Yokohama was 11:48 in Tokyo and 11:38 in Osaka. That worked for a feudal society. It failed for railways, telegraphs, and steamships.
On 1 January 1888, the Meiji government set a single reference time tied to the 135°E meridian. Yokohama, a major international port, adopted it immediately. A later ordinance in 1895 formalised the rule, but the offset stayed the same. Japan has been UTC+9 ever since.
Who keeps the time
The National Institute of Information and Communications Technology (NICT) maintains Japan Standard Time. Its atomic clocks sit in Koganei, Tokyo, about 30 kilometres north of Yokohama.
NICT distributes the time three ways. NTP servers at ntp.nict.jp serve computers and networks. JJY radio signals broadcast on 40 kHz from Mount Otakadoya in Fukushima and 60 kHz from Mount Hagane in Kyushu. Radio-controlled clocks use these. A telephone service at 117 gives a spoken time announcement.
Most public clocks in Yokohama, stations, government buildings, shopping centres, sync to the JJY signal. Phones and computers sync over the network.
Yokohama does not observe daylight saving
No. Yokohama does not observe daylight saving time in 2026 or 2027. The offset stays UTC+9. No legislation is pending.
Japan tried DST under Allied occupation. The country observed it for three summers: 1948, 1949, and 1950. It was abolished in 1952 after sovereignty returned. Farmers and workers opposed it. They saw it as extending work hours.
After the Fukushima disaster in 2011, the Ministry of Economy, Trade and Industry studied DST as an energy-saving measure. The study concluded that reprogramming IT systems, disrupting transport schedules, and shifting daily life cost more than the negligible energy benefit. The proposal died. No active legislation exists today.
JST vs other abbreviations
JST is shared between two time zones. This causes confusion.
| Abbreviation | Full name | Offset | Location | |---|---|---| | JST | Japan Standard Time | UTC+9 | Japan | | JST | Jerusalem Standard Time | UTC+2 | Israel (winter only; switches to IDT in summer) |
If a meeting says "10:00 JST", check whether the organiser means Japan or Jerusalem. Write the offset: "10:00 JST (UTC+9)" for Yokohama.
Yokohama shares its offset with Korea Standard Time (KST), Yakutsk Time, and Palau Time. A full list is on the UTC+9 countries page.
Quick reference: Yokohama time zone facts
| Item | Details |
|---|---|
| Time zone name | Japan Standard Time (JST) |
| UTC offset | UTC+9 (year-round) |
| Daylight saving | None |
| IANA identifier | Asia/Tokyo |
| Reference meridian | 135°E (passes near Akashi) |
| Yokohama solar noon | ~11:42 JST |
| Timekeeper | NICT, Koganei, Tokyo |
| DST history | 1948-1950 (abolished 1952) |
| Current DST proposals | None |
What is the time difference between Yokohama and New York?
On 15 January 2026, New York is 14 hours behind Yokohama. On 15 July 2026, it is 13 hours behind. The gap changes because New York observes daylight saving and Yokohama does not.
Does Yokohama use the same time as Tokyo?
Yes. All of Japan uses a single time zone, Asia/Tokyo. Yokohama and Tokyo share the same clock.
Why is solar noon in Yokohama before 12:00?
Yokohama sits east of the 135°E reference meridian. The sun reaches its highest point about 18 minutes before the clock reads noon. Normal for the eastern edge of a time zone.
When did Japan start using a single time?
Japan adopted a unified reference time on 1 January 1888, set to the 135°E meridian. Before that, each city used local solar time.
Does Japan ever change its clocks?
No. Japan has not observed daylight saving since 1951. The government studied it after the 2011 Fukushima disaster and rejected it.
Is JST the same as KST?
Yes. Japan Standard Time and Korea Standard Time both use UTC+9. Seoul and Yokohama always show the same hour.