The Mount Merbabu National Park Office (BTNGMb) has urged hikers to increase vigilance following an extreme drop in air temperatures in the mountain's peak area. This natural phenomenon, known locally as bediding, has triggered the formation of frost as temperatures plummeted to minus 1 degree Celsius.
BTNGMb Public Relations Officer, Dian Saraswati, confirmed that based on temperature measurements in the Pos Sabana 1 area on July 9–10, 2026, air temperatures continued to drop drastically starting at night. While at 8:00 PM WIB the temperature stood at 6 degrees Celsius, by early morning before dawn at around 5:30 AM WIB, it plummeted to minus 1 degree Celsius with a humidity level of 46 percent.
According to the Meteorology, Climatology, and Geophysics Agency (BMKG), the extreme temperature drop on this 3,145-meter-high mountain above sea level (masl) is part of a normal cycle during the peak of the dry season. This extreme cold weather phenomenon affecting the mountainous area is predicted to last until September 2026.
Given the extremely cold weather conditions accompanied by strong winds, BTNGMb warned of a high risk of hypothermia for hikers. Early symptoms to watch for include severe, continuous shivering, paleness or blueness of fingertips and lips, decreased concentration, and sudden bodily weakness accompanied by severe drowsiness.
If hikers begin to experience these symptoms, officials advise them to immediately stop their journey and seek safe shelter from the wind. The first response steps that can be taken include replacing wet clothing with dry clothes, warming the body slowly, and consuming warm drinks.
Head of BTNGMb, Anggit Haryoso, emphasized that life safety must be the top priority over the scenic beauty of the dry season. He asked hikers to thoroughly prepare physically and bring standard equipment, as well as understand disaster mitigation to ensure all group members can return home safely.
