JAKARTA - The phenomenon of frost or bun upas has once again enveloped the Arjuna Temple area, Dieng Kulon Village, Dieng Plateau, Banjarnegara Regency, Central Java, in recent days as the dry season approaches.
The Secretary of Dieng Kulon Village, Sabar Alfarisi, said that the appearance of frost began to be seen since the last few days as the air temperature continued to decrease at night and in the morning.
"It has been about the last three days that frost has started to appear in Dieng. The spread is visible around the Arjuna Temple area and other open areas," he said as quoted by ANTARA, Tuesday, June 9.
According to him, the natural phenomenon that is the hallmark of the dry season in Dieng always attracts tourists.
Therefore, he said, many visitors came early in the morning to witness and capture the formation of a thin layer of ice crystals on the surface of the grass and plants.
"There are many tourists who come to see and take photos of the frost. This phenomenon is always a special attraction for visitors to Dieng," he said.
The Head of the Meteorology, Climatology and Geophysics Agency (BMKG) Central Java Climatology Station Goeroeh Tjiptanto said the emergence of bun upas this year was triggered by dry weather conditions in the last few days.
Based on BMKG data, he said, rainfall in the Dieng area in the period of June 6-9, 2026 was recorded at 0 millimeters.
"Zero millimeter rainfall indicates that the atmosphere is in a very dry condition. In addition, the sky tends to be clear without clouds at night and in the morning," he said.
He said the absence of cloud cover made the heat stored on the earth's surface during the day released to the maximum to the atmosphere and space at night.
According to him, this condition resulted in the cooling process taking place quickly so that the surface temperature of the ground dropped drastically.
"Based on data, the minimum air temperature in Dieng on June 9, 2026 reached 1.05 degrees Celsius at 01.01 WIB. Meanwhile, the temperature of the grass or the ground surface was recorded lower, namely 0.60 degrees Celsius at 08.30 WIB," he said.
According to him, this condition allows the formation of a thin layer of ice crystals on grass, agricultural plants, and other surfaces that are directly exposed to cold air.
He said that the topography of Dieng in the form of a basin and surrounded by mountains also strengthened the formation of frost.
"Cold air from the mountain slopes moves down at night and is trapped at the bottom of the valley so that the temperature in the area is much lower than the surrounding area," he said.
Regarding this, Goeroeh appealed to the public and tourists visiting Dieng to prepare warm clothes and be aware of the extreme cold temperature which is expected to still have the potential to occur in the next few days, especially at night and in the morning.
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