The Meteorological Department announced that temperatures are set to fall in the North and Northeast as a strong high-pressure system from China moves into upper Thailand.
A drop of 6-8°C is forecast for the plains areas, with overnight minimums of 8-16°C, from Wednesday 30th December to 3rd January 2021.
On mountaintops, it will be cold to very cold, with minimum temperatures of 2-10°C bringing isolated morning frosts.
In the Central and East regions, minimum temperatures will likely range from 15-22°C.
People are advised to watch their health.
With a stronger northeast monsoon across the Gulf of Thailand and the South, waves will be about 2 metres high in the upper part of the Gulf, 2-3m in the lower part and more than 3m high during thundershowers.
Residents along the coastline should beware of inshore surges. All vessels should proceed with caution. Small boats are advised to remain ashore from 31st December to 3rd January, the weather office said.