The north and Northeast Thailand are going to experience the first cold spell of this year when temperature will drop by 3-5 degrees Celsius during the next few days.
But in the mountainous areas temperatures have already plunged below 20 degrees Celsius.
Thailand Meteorological Departmentbp said heavy fog has blanketed parts of Nan province during the morning due to arrival of cold spells.
It advised commuters to be on extra cautious when traveling in the Northern routes.
The lowest ground-level temperature in the province has reached 22 degrees Celsius by today, whereas the average temperature on top of the mountains are somewhere between 17-18 degrees Celsius.
Tourists traveling to national parks situated atop the mountains are advised to prepare themselves with proper clothing and carefully study their routes before traveling to such areas.
Elsewhere in Loei province, a thick layer of fog has covered many parts of the roads.
Locals and tourists have been warned to be extra cautious, as the fog caused poor visibility in driving to less than 100 metres.
The weather forecast department has reported that from October 6-11, a strong high pressure cell coming in from China is set to cover parts of the North and Northeast.
Gusty winds and thunderstorms are expected to follow as a result of this phenomenon.
A monsoon trough coming in from the South will also cause increased rainfall in the southern region and heavy rains in some areas.
Cold spell is coming - Thai PBS English News