Thailand Braces for Heavy Rain from Tropical Storm Maysak
Tropical Storm Maysak is expected to bring heavy rainfall to Thailand's North, Northeast, East, and Southern regions from July 3-6, with authorities activating daily briefings and disaster alerts to monitor flash floods and landslides.
Thailand's National Water Resources Office (ONWR) is joining forces with the Department of Disaster Prevention and Mitigation to prepare for severe rainfall from monsoon troughs and Tropical Storm Maysak. Secretary-General Chayant Mueang Song reported that a monsoon trough is currently crossing the North and upper Northeast, while the southwest monsoon is bringing strong winds across the Andaman Sea, Thai waters, and the Gulf of Thailand. A depression in the northern South China Sea has intensified into Tropical Storm Maysak, which is expected to move toward Hainan Island and northern Vietnam on July 4-5, 2026, indirectly impacting Thailand with heavy to very heavy rainfall in the upper Northeast, North, East, and western Southern regions. This could trigger flash floods, flash floods from runoff, and landslides.
The ONWR's National Water Operations Center holds regular situation briefings daily at 7:30 AM and 4:30 PM to analyze rainfall patterns, assess severity, and identify at-risk areas before distributing information to regional ONWR offices for management. If at-risk areas for flooding, flash floods, or landslides are identified, the office will immediately coordinate with the Department of Disaster Prevention and Mitigation to issue public alerts via Cell Broadcast technology. From July 3-6, 2026, high-risk provinces requiring special monitoring include Chiang Rai, Nan, and Phayao in the North; Chanthaburi and Trat in the East; and Phang Nga, Phuket, Ranong, and Krabi in the South.
The office continues to closely monitor and manage water levels in reservoirs and water releases to align with rainfall and storm conditions. Currently, national water sources hold 44,137 million cubic meters, or 55 percent of storage capacity, with usable water at 20,026 million cubic meters, or 35 percent. The office continuously tracks inflow to reservoirs to adjust water release plans appropriately, ensuring flood management capacity during monsoon season and water conservation for the dry season as Thailand faces El Niño conditions.
From June 25 to July 1, 2026, 35 major reservoirs nationwide received 331 million cubic meters of water, distributed across regions: North (9 reservoirs, 98 million cu.m.), upper Northeast (12 reservoirs, 45 million cu.m.), Central (2 reservoirs, 12 million cu.m.), East (6 reservoirs, 8 million cu.m.), West (4 reservoirs, 107 million cu.m.), and South (2 reservoirs, 61 million cu.m.). The top five reservoirs by inflow are Vajiralongkorn, Sirikit, Bhumibol, Ratchaprapha, and Srinakarin dams.
Meanwhile, the ONWR remains vigilant about drought-prone areas during July 2026 due to rainfall gaps, having compiled data on water-scarce regions nationwide covering domestic consumption, agriculture, and water quality. The office coordinates with relevant agencies to continuously monitor, analyze, and assess water situations under the Water Resources Management Committee to adjust management criteria accordingly.
