The temperature, especially in upper Thailand, is predicted to fall slightly until Dec 27 as a new high-pressure area is spreading into the upper part of the country, while the South is being warned to brace for more rain, the Thai Meteorological Department (TMD) said.
At the beginning of this new cold spell, from yesterday till Monday, rain is expected in the lower part of the Northeast, the East, and Central regions, including Bangkok and its surrounding provinces.
This is because the cold air is expected to meet a tropical phenomenon called an "easterly wave", an atmospheric trough that usually causes cloudy areas rife with thunderstorms, the department said yesterday.
From tomorrow, most parts of upper Thailand will then experience colder and drier weather without rain, especially in hilltop areas, which could last until after Christmas, said the TMD.
The lowest temperature recorded at Ang Khang Royal Agricultural Station in Fang district of Chiang Mai, for instance, was 8.4C.
The South, from Prachuap Khiri Khan downward, will, during the same period, have less rain while still needing to prepare for strong winds and high sea waves, the department added.
From yesterday until Monday, the temperature is forecast to drop by 4 to 8C in the Northeast and by 2 to 5C in the North, the East and Central regions, including Bangkok and the suburbs.
In related news, the Department of Disease Control (DDC) is warning of a possible uptick in cases of respiratory diseases, especially influenza.
From Jan 1 until Nov 30, Thailand recorded 630,786 cases of the flu, including 47 deaths, said Dr Panumas Yannawetsakul, director-general of the DDC.