Typical weather during the rainy season in northern Thailand

General Weather Conditions

From mid-May to mid-June, Thailand experiences a steady increase in rainfall, with 40-60 percent of the area receiving heavy rain. In the east and southwest, 60-80 percent of the region experiences heavy rain. In some places, the southwest monsoon periodically covers the Andaman Sea and Thailand. The monsoon track passes through the upper part of Thailand periodically.

     In addition, during specific periods, low pressure will build up in the Andaman Sea and increase into a depression or cyclone and move closer to the west side of Thailand.

Then, from mid-June to mid-July, rainfall and rainfall distribution will be reduced, which may cause a shortage of agricultural water in many areas, especially drought-prone areas outside the irrigation zone. In addition, the southwestern monsoon that covers the Andaman Sea and Thailand will weaken, and the monsoon trough will move up through the southern part of China.

From mid-July to September, Thailand resumes heavy rainfall, with 60-80 percent of the area getting heavy rain in some places, causing flooding, flash floods, and overflows in different areas. Because of the southwest monsoon that covers the Andaman Sea, Thailand resumes intense intermittent and continuous rainfall, with the monsoon track sliding down through the upper region periodically.    

In October, the northern and northeastern regions have reduced rainfall distribution and start to get cooler in the morning, especially in the upper part of the region. However, the central, eastern, and southern regions continue to experience heavy rainfall and heavy rainfall in some areas. As the high pressure from China starts to spread down the upper part of the northern and northeastern regions, the monsoon will slide down through the lower central, upper southern, and eastern regions. In addition, the southwest monsoon that covers Thailand will begin to turn into the northeastern monsoon, instead.

Expected general weather in the North 
     In May, July, September, and October, the total rainfall is expected to be 5-10 percent higher than usual (average values 173, 189, 222, and 117 mm, respectively). In June, total rainfall is similar to average values, usually 153 mm. For August, total rainfall is 5 percent less than average values, usually 237 mm.

Cautions:

1. There can be heavy rains for several days in a row. As a result, flash floods and overflows may occur, especially from August to September. Therefore, the public is requested to monitor the daily weather news closely.
2. During tropical storms that move closer to or through Thailand, there will be strong winds, heavy rainfall in wide areas, and heavy rainfall in many areas. As a result, in coastal areas, there will be strong wind and high waves. The height of the waves can be up to 3-4 meters at some point. Therefore, people and boaters are advised to be careful of the danger of natural disasters and to monitor the news closely during tropical storms.

Source:  Northern Meteorological Center, Chiang Mai Airport Road, Suthep, Muang District, Chiang Mai 50200. Tel. 0 5327 5463

For more information