A new cold air mass from China is descending over the upper northeast, covering the upper eastern, upper central and upper northern regions, and is expected to extend further over the lower northeastern, lower central and lower northern regions as the week progresses.
A strong easterly wind meanwhile is affecting the eastern and central regions, while the weather in the south is being influenced by low atmospheric pressure leading to heavy to very heavy rainfall in some areas.
In the Gulf of Thailand and the Andaman Sea, waves of 1-2 metres, or higher in areas with thunderstorms can be expected. Small vessels are advised to navigate with caution.