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Lang Son, Vietnam

Lang Son uses Vietnam’s national time, Indochina Time (UTC+7). Its clocks stay unchanged throughout the year, although sunrise and sunset move with the seasons and differ slightly from one locality to another.

Lang Son, Vietnam

Friday, 4 September 2026

UTC+7 · Asia/Ho_Chi_Minh

Time and sun data for Lang Son — the largest city of Lang Son

The sun in Lang Son

Sunrise 05:38 Solar noon 11:54 Sunset 18:09 Daylight 12 h 31 min Night 11 h 29 min Civil twilight 05:15 – 18:32

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Current time in Lang Son, Vietnam

The clock on this page represents local time across the Lang Son region. The city of Lang Son, border communities such as Dong Dang, and settlements elsewhere in the area all keep the same civil time.

There is no daylight saving adjustment. Local clocks are not advanced for summer or turned back later in the year. This makes domestic scheduling straightforward, since Lang Son shares its offset with Hanoi and every other part of Vietnam. At the border, documents may change hands; the clock does not need to.

Urban centres and one shared clock

Lang Son city is the region’s principal urban centre. Dong Dang is also widely known because of its position near the international border and its transport connections. Other notable local centres include Cao Loc and That Khe.

Lang Son city follows UTC+7. Dong Dang keeps the same time as Lang Son city. Cao Loc requires no time adjustment. That Khe remains on Vietnam’s national clock. The list identifies useful reference points rather than separate clock zones. A bus or road journey within Lang Son can cross mountainous terrain and take longer than a map initially suggests, but arrival times remain expressed in the same zone. Border timetables should still be read carefully because a destination outside Vietnam may use another official time.

Understanding sunrise in Lang Son

Lang Son lies in northern Vietnam, where the annual change in daylight is more noticeable than it is nearer the equator. That does not alter the UTC offset. It changes only when daylight begins and ends according to the clock.

A sunrise time is tied to a date and a location. Two towns can share UTC+7 yet receive sunrise at slightly different moments because they are not on the same longitude. Mountains further complicate what an observer sees: the Sun may have risen geometrically while a ridge still blocks direct light.

Anyone planning a border departure, market visit, hike, or morning photograph should use the sunrise entry for the closest available locality. Civil twilight provides some light before sunrise, but visibility can also be affected by clouds, haze, and the immediate landscape. A forecast and a sunrise calculation answer different questions and are most useful together.

Questions and answers

How far ahead of UTC is Lang Son?
Lang Son is seven hours ahead of Coordinated Universal Time.
Is Lang Son on the same time as Hanoi?
Yes. Both places use Indochina Time throughout the year.
Why might the Sun appear after the published sunrise?
A nearby mountain, building, or other obstruction can hide direct sunlight after the astronomical sunrise has occurred.
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