In its latest forecast Monday, the department said the westerly wind is still blowing pass the North into the upper northeastern region.
The combination of wind and cold spell will result in turbulent weather in both regions this week, and torrential rains.
It said after the rains temperatures in the upper region of the country will drop 4-6 degrees.
Meanwhile the moderate northeasterly monsoon is still covering the South and the Gulf of Thailand, thus causing scattered rains from Nakhon Si Thammarat downwards, and 2-3 metres high waves in the lower areas of Gulf.
For Bangkok and surrounding provinces, cloudy sky and scattered light rains were expected covering 10 percent of areas, and lowest temperatures were between 20-23 degrees and maximum temperatures at 29-30 degrees.