Time in Thailand

History

• Prior to 1 January 1901, locations in Siam with an astronomical observatory would adopt local mean time based on the observatory's geographic position. Chiang Mai Province and two other provinces each had an observatory, hence, each province had its own distinct local mean time, with minutes of difference between the three locations.
• On 1 April 1920, the mean time of the 105th meridian east (passing through Ubon Ratchathani Province) was adopted by Siam as the new standard time. The mean time of the 105th meridian is 7 hours ahead of Greenwich Mean Time (i.e., local mean time at the Greenwich Royal Observatory).
• There are attempts to shift Thailand's timezone to UTC+08:00. In 1993, the Minister of Commerce at that time proposed that plan to boost the competitveness of the country. In July 2001, Thailand announced its intention of moving its time forward one hour, to align with both Malaysia and Singapore and more importantly with Western Australia, Philippines, Central Indonesia, and Taiwan, i.e., . This was met with much criticism and resistance and the plan was withdrawn.