The time zone in Thailand is Indochina time (ICT +7 GMT). During the European summer, ICT is +6 hours from GMT and in the European winter, ICT is +7 hours when compared to GMT.
Due to Bangkok's proximity to the equator (13' north), summer sun-rise on mid-summer's day (21st June) is at about 5.50am and sunset is at about 6.50pm with 20 minutes of twilight either side. In winter (December 21st), the sun rises at about 6.40am and sets at 6.00pm with similar twilight as the summer. The longest summer day has 12 hours 56 minutes of daylight and the shortest winter day has 11 hours 20 minutes.