October 17, 2025
JAKARTA – Southern Indonesia is expected to experience extreme heat until the end of the year, as both minimal cloud cover over the islands and the ongoing pancaroba (the transitional period between the dry and rainy seasons) allow for intense solar radiation to directly heat the land, authorities warned.
The Meteorology, Climatology and Geophysics Agency (BMKG) has subsequently urged the public to limit outdoor activities to reduce health risks from prolonged heat exposure.
Between Oct. 13 and 14, BMKG recorded daytime temperatures ranging from 27 to 35 degrees Celsius in several major urban centers, including Jakarta, Surabaya, East Java, Palembang, South Sumatra, Semarang, Central Java and Denpasar, Bali. The hottest reading during this period was recorded in South Tangerang, Banten, surpassing 37 degrees Celsius.
Jakarta residents have been particularly affected by soaring daytime temperatures, with highs reaching 35 degrees Celsius, approximately three degrees above the city’s average for this time of year. The situation is compounded by worsening air quality in the capital, making outdoor activity more taxing.
BMKG meteorology deputy Guswanto told The Jakarta Post on Wednesday that extreme heat is expected to continue until December or early 2026.
“We urge the public to minimize heavy physical activities outdoors, particularly for the elderly and children,” he said.
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The prolonged high temperatures are driven primarily by intensified solar radiation over southern Indonesia, particularly Sumatra, Java and Bali. “[These regions currently] have minimal cloud cover, allowing sunlight to reach the earth’s surface directly with little obstruction,” Guswanto explained.
The country is also entering the pancaroba phase, which is often characterized by elevated temperatures and unpredictable weather patterns, he added.
Experts say the extreme heat experienced in urban areas is intensified by human-made factors.
Beta Paramita, a green urban expert at the Indonesian Education University (UPI), explained that materials such as asphalt and concrete absorb solar heat during the day and re-emit it into the surrounding environment, increasing ambient temperatures.
Urban emissions also trap heat in the atmosphere, contributing to higher temperatures, Beta said, adding it was essential to make improvements in urban planning and green infrastructure “to make Jakarta a thermally comfortable city”.
Budi Haryanto, an environmental health researcher at University of Indonesia, warned that recent scorching temperatures have exceeded the human body’s tolerance for external heat.
Although the body can handle considerable temperature fluctuations, the optimal range is between 15 and 32 degrees Celsius, he said.
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Exposure to higher temperatures can cause dizziness, fatigue and nausea, and for heat-sensitive individuals, prolonged heat may trigger cardiovascular problems, emotional stress and reduced focus.
Staying hydrated is crucial, said Budi, encouraging people to balance water intake with mineral or electrolyte drinks to replace nutrients lost through excessive sweating.
He also urged authorities to develop a more comprehensive extreme heat alert system, including regularly updated and widely distributed local temperature reports.
“This would help outdoor workers and others exposed to direct sunlight to adapt safely to higher temperatures,” Budi concluded.