24 May 2023

Brunei Darussalam will be transitioning from inter-monsoon phase to Southwest Monsoon which is expected to start around the final week of this May. Typically, Southwest Monsoon will persist until September. During Southwest Monsoon, atmospheric conditions over our country tend to be quite stable with minimal thundershowers occurrences.

The wind condition generally will be blowing from the Southwest direction during this period. Southwest Monsoon is also synonym with the season of active development of tropical storm and typhoon systems
over the Northwest Pacific Ocean and the South China Sea. Hence, our country’s weather could be influenced by the presence of these tropical storm or typhoon systems. However, it depends on the distance of their locations from our country.

The influence of tropical storm or typhoon systems nearby our region may bring about the development of squall line phenomena which will cause the country to experience unsettled weather conditions with thunderstorms and occasional gusty winds. A squall line is fast-moving cells of thunderstorms in a long, narrow line formation. Meanwhile in August, usually our country will be experiencing hazy conditions due to dry weather across the Southeast Asian region.

According to our climatological data, the normal rainfall amount recorded at our Meteorological Observation Station at Brunei International Airport for the month of June, July, August and September are 237.7 mm, 241.8 mm 231.5 mm and 235.1 mm respectively. However, with reference to several international climate models, rainfall amount for our country for the month of June and July are expected to be at normal range which is between 190 mm to 240 mm, whereas for August and September will be at slightly below normal range which is between 140 mm to 190 mm.

We shall continue to monitor the weather conditions and will issue weather advisories or warnings if necessary. Latest weather information, advisories and warnings can be accessed easily through our mobile app, Brunei WX, as these weather information, advisories and warnings can be received immediately after they are issued. Latest weather information can also be obtained by contacting the duty meteorological forecaster at our Forecast Centre, through our Weather Line 114, by visiting our website at or follow our Facebook (@bruneiweather), Instagram ( and our Telegram Channel (Brunei Weather).

Wallahu a’lam Bissawab.