RRI.CO.ID, Bogor - Cooler nighttime and early morning temperatures have recently been felt across several Indonesian regions, especially on Java Island. This seasonal cold spell, locally known as bediding, is not directly caused by climate change but by normal atmospheric processes.

Dr. Givo Alsepan from the Department of Geophysics and Meteorology, Faculty of Mathematics and Natural Sciences, said IPB University, bediding is a regular seasonal phenomenon. He explained that it typically occurs between June and September as part of Indonesia's dry season climate.

Climate change does not directly cause the cold spell, although it can influence several characteristics of the phenomenon over time. These effects include shifts in the dry season's onset, humidity levels, clear night frequency, and the duration of cooler temperatures.

"Bediding is a normal atmospheric phenomenon during the dry season. It is not an isolated event but rather the manifestation of atmospheric physical processes," Dr. Givo said on IPB University website on Wednesday, July 22, 2026) He said the phenomenon occurs when daily minimum temperatures drop significantly because nighttime radiative cooling becomes highly effective.

Dr. Givo explained that clear skies during the dry season play a major role in strengthening radiative cooling. With fewer clouds, heat absorbed by the Earth's surface during daylight escapes more easily into the atmosphere and outer space.

He added that the atmosphere is generally much drier during the dry season than during the rainy season. Lower water vapor levels reduce heat retention, allowing surface temperatures to fall more rapidly throughout the night.

According to him, bediding becomes more noticeable in mountainous and highland regions because of higher elevations and cold air accumulation. In areas such as the Dieng Plateau, these conditions may even trigger frost formation.

He also noted that the Australian Monsoon strengthens bediding by bringing cooler and drier air masses toward Indonesia. Southern regions near the equator, including Java, Bali, and Nusa Tenggara, experience the greatest influence from this seasonal wind pattern.

Dr. Givo added that the developing El Niño phenomenon could further intensify dry season conditions across Indonesia. Lower rainfall, reduced humidity, and more frequent clear nights allow radiative cooling to occur more efficiently, increasing the likelihood of bediding.

He advised the public to protect their health, especially children, older adults, and people with respiratory illnesses. Dr. Givo also encouraged residents to stay hydrated, remain alert for forest and land fires, and continue monitoring weather and climate information issued by the Meteorology, Climatology, and Geophysics Agency.