'Bediding' Phenomenon Hits Java, Dieng Records Coldest Temperature

Many social media users have recently complained about the air feeling much colder, especially at night and in the early morning. This phenomenon, commonly referred to as ‘bediding’, typically occurs during the dry season and is being felt across several regions of Java. The Meteorology, Climatology, and Geophysics Agency (BMKG) explained that the cold temperatures are influenced by several factors, one of which is the strengthening of the Australian monsoon. This wind system carries dry air masses that reduce water vapour content and cloud formation in the atmosphere. The lack of cloud cover allows heat from the earth’s surface to escape more easily into the atmosphere at night, causing air temperatures to drop significantly, particularly just before dawn. Based on BMKG data from the past decade, the temperature drop begins to be felt in July and peaks between July and August. For example, in Malang Regency, temperatures can drop to below 19.5 degrees Celsius, which is much colder compared to Jakarta, where temperatures remain relatively stable and warm. This demonstrates the role of topography and highland elevation in trapping cold air. Nighttime observations using Land Surface Temperature (LST) maps from the MODIS sensor on weather satellites also show low-temperature zones stretching along the mountain ranges of Java, indicating that highland areas are the most affected by the bediding phenomenon. Dr Givo Alsepas, a lecturer in the Department of Geophysics and Meteorology at IPB University, estimates that this phenomenon could last until the peak of the dry season, around late July to August, and in some areas may continue until early September, depending on atmospheric developments. Indonesia is currently experiencing the dry season influenced by the Australian monsoon, while Europe, North America, and parts of East Asia are entering their summer. The BMKG noted that some highland areas are experiencing extremely low temperatures, such as Mount Bromo and the Dieng Plateau. Data from the BMKG’s Automatic Weather Station (AWS) recorded a temperature of 3.9 degrees Celsius at Bromo on 11 June, but Dieng recorded the lowest temperature, almost reaching freezing point at 0.7 degrees Celsius. The cold is so intense in highland areas like Mount Bromo that dew on leaves can freeze into ice crystals, resembling a layer of snow. To stay healthy during this cold spell, the BMKG advises the public to ensure adequate nutritional intake and consume warm drinks to maintain immunity, as well as to use moisturiser to prevent dry and cracked skin.