The Thai Meteorological Department forecasts thunderstorms across 60% of Bangkok and surrounding provinces, plus isolated heavy rain in the north and northeast, with flash-flood and run-off risk near waterways and low-lying areas. If your shop, warehouse or delivery routes sit in those zones, plan for possible flooding, stock off the floor, and allow extra time for transport. Small-vessel operators in the Andaman Sea and Gulf should note waves of 1-2 metres and possibly above 2 metres during storms.