The National Water Resources Office (สทนช.) warns of heavy-to-very-heavy rain on 19-21 Aug 2026 from a monsoon trough over the North and upper Northeast, with flash floods, mountain runoff and landslides possible. The article lists 17 provinces to watch (North, Northeast, East, Kanchanaburi), and notes the official list has 17 rather than the 18 cited in the headline. Rain is forecast to increase again 18-22 Aug in the North and upper Northeast. If your shop, warehouse, farm or delivery routes are in these areas, move stock off low floors, plan alternative routes and check on staff and supplier deliveries. Reservoirs nationally are at 60% capacity, so water supply is not the immediate concern.