BANDAR SERI BEGAWAN: Brunei Darussalam has entered the Southwest Monsoon season, which is expected to persist until September, bringing generally more stable weather conditions, fewer thunderstorms and the possibility of drier-than-normal conditions in the coming months.
In a statement, the Brunei Darussalam Meteorological Department (BDMD) said the Southwest Monsoon is characterised by more stable atmospheric conditions compared to the inter-monsoon season, resulting in fewer occurrences of thunderstorms.
During the peak of the monsoon period, typically around August, the country may experience hazy conditions due to generally dry weather prevailing across the South-East Asian region.
The department also noted that the Southwest Monsoon coincides with the active development of tropical storms and typhoon systems over the Northwest Pacific Ocean and the South China Sea. Although these weather systems usually develop far from Brunei, their proximity and intensity can still influence local weather conditions.
Such systems may trigger the formation of squall lines – fast-moving bands of thunderstorms arranged in a long, narrow formation – which can bring unsettled weather, including gusty winds and occasional thunderstorms.
According to climatological records from the Weather Observation Station at Brunei International Airport, normal rainfall amounts for June, July and August are 237.7 millimetres, 241.8 millimetres and 231.5 millimetres respectively.
BDMD said climate model outlooks from international forecasting centres indicate that large-scale atmospheric conditions, particularly the El Niño–Southern Oscillation (ENSO), are expected to influence regional weather patterns between June and August 2026.
ENSO conditions are forecast to remain in the El Niño phase during the period, with a probability of approximately 92 per cent. El Niño conditions are typically associated with reduced rainfall activity, higher temperatures and lower relative humidity in Brunei Darussalam.
Based on the long-range outlook, rainfall in June is expected to be slightly below normal, while July is forecast to receive between 140 and 190 millimetres of rainfall, also slightly below normal. August is expected to be drier, with rainfall forecast to be below normal at 140 millimetres or less.
The department said it will continue to monitor weather developments and issue advisories or warnings when necessary. - Borneo Bulletin/ANN
