Th weather office announced the start of summer on Wednesday, with a forecast for temperatures to rise to a blistering 45°C. (Bangkok Post)The Meteorological Department has announced the start of summer, with temperatures expected to peak at a blistering 45°C over the next few months in some areas. Meanwhile, people gathered to enjoy a late frost at the top of Thailand's highest mountain, in Chiang Mai, on Thursday morning. In lowland areas of Chiang Mai province, temperatures were 14-16°C. Frost coats leaves at the top of Doi Inthanon in Chiang Mai province on Thursday morning, as the Meteorogical Department announced the start of a hot, dry summer.