General Situation
18 May 2026
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Weather Map
The rather strong southwest monsoon prevaills over the upper Andaman Sea and Thailand while the low pressure cell covers the coast of upper Vietnam. Isolated heavy rains are forecast in the North, the Northeast and the Cenral while isolated very heavy rains are possible in the East and the South (west coast). People should beware of heavy to very heavy rains and accumulation that may cause flash floods and overflows, especially along waterways near foothills and lowlands.
The rather strong wind forces the waves in the upper Andaman Sea up to be 2–3 meters high and above 3 meters high in thundershowers. In the lower Andaman Sea and the upper Gulf, the waves are expected to be about 2 meters high and above 2 meters high in thundershowers. All ships should proceed with caution and keep off thundershowers, small boats in the upper Andaman Sea keep ashore.
Bangkok Metropolis and Vicinity Forecast
06:00 Today - 06:00 TomorrowScattered thundershowers. Minimum temperature 26-28 °C. Maximum temperature 34-36 °C. Southwesterly winds 10-20 km./hr.
Announcement Date 18 May 2026
Weather Province Additional
7 days Weather Forecast
Weather Outlook During 18 – 24 May 2026Forecast
During 18 - 21 May 2026, the rather strong southwest monsoon prevails across the Andaman Sea, Thailand and the Gulf while low-pressure cell cover upper Vietnam and the Gulf of Tonkin. Continuous rainfalls and isolated heavy to very heavy rains are forecast in the western part of the North and the Central, the upper Northeast, the East and the South. The rather strong winds force the waves in the upper Andaman Sea up to be 2 - 3 meters high and above 3 meters high in thundershowers. In the upper Gulf, the waves are expected about 2 meters and above 2 meters in thundershowers. During 22 - 24 May 2026, the southwest monsoon prevailing over the Andaman Sea, Thailand and the Gulf will weaken. Less rains are likely in the country but isolated heavy rains are possible in the western part of the North, the Central and the South. The weakening winds and waves in the upper Andaman Sea are expected about 2 meters high, 1-2 meters high in the lower Andaman Sea and the upper Gulf and above 2 meters high in thundershowers.
Caution
People should beware of heavy to very heavy rains and accumulation that may cause flash floods and overflows especially along the waterways near foothills and lowlands. All ships in the Gulf and Andaman Sea should proceed with caution and keep off thundershowers throughout the period, small boat in the upper Andaman Sea keep ashore during 18 – 22 May 2026.
Announcement Date 18 May 2026
7 day Weather Summary
11 May 2026 - 17 May 2026Forecast
The high-pressure area from China extended its ridge to cover the northeastern region of Thailand and the South China Sea was weakened and mostly covered the South China Sea. Additionally, the southerly and southeasterly winds prevailed over upper Thailand at the beginning of the week. After that the southwesterly winds prevailed over upper Thailand. These conditions caused hot weather in several areas while rainfall occurred almost the week in upper Thailand with thunderstorm and gusty wind were reported in several areas. For the southern region, the easterly wind prevailed over the Gulf of Thailand and the southern region, which strengthened at the beginning of the week. After that, the southwesterly wind blew over the Andaman Sea, the southern part and the Gulf of Thailand in the second half of the week, causing abundant rainfall almost the week.
Announcement Date 18 May 2026
Previous
Monthly Weather Forecast
November 2022Forecast
Upper Thailand will be more cold especially the northern and northeastern regions with some thunderstorms on certain days. For the mountain tops, mountain peaks, and mountain ranges, the weather is generally cold. This is because The high pressure area from China will extend to cover the North and Northeast periodically. It will be mostly moderate power. the southern part It continues to rain heavily. especially the east coast from Chumphon down There are still thunderstorms in 60 - 80 percent of the area with heavy rain in many areas and very heavy in some places.This will cause flash floods and flash floods, as well as overflowing riverbanks in some places. For wind waves in the Gulf of Thailand will be strong. In some periods, there will be waves 2 - 4 meters high, while the Andaman Sea will have 1-2 meters high because the northeast monsoon still prevails over the Gulf of Thailand and the South. It will have strength from time to time. In addition, there will be a monsoon trough that lies across the central South in some periods. In addition, in some periods there will be an active low pressure cell moving closer. and has a high chance of moving through the southern region
Caution
In summary, this month, the total rainfall in the northern and northeastern regions is expected to be 10% less than normal, and the central and eastern regions are close to normal. The southern region is 10 percent above normal, while the average landscape is still slightly above normal.
Announcement Date 01 November 2022