BMKG has initiated cloud-seeding operations to extinguish the forest and land fires in the Lake Toba area, running from July 26 to July 31, 2025. “As we entered the third day of weather modification, we’ve observed precipitation in parts of northern Toba, southern Toba, and a small area in Samosir. The success of this operation depends on the potential for clouds and wind. Yesterday, the conditions for both did not cover all of Toba, so our efforts to create rain were only partially successful,” stated Hendro Nugroho, Head of BMKG Region I, to detikSumut on Monday, July 28, 2025.
Nugroho further noted that the air temperature in the Lake Toba area is quite conducive for cloud formation, being lower than temperatures in Medan.
The cloud-seeding trials commenced on July 26, 2025, with two sorties conducted, followed by three sorties on July 27. “The temperature in Toba is normal, unlike Medan where it can reach 38 degrees Celsius. Here, it hovers around 30-32 degrees, which is ideal for cloud development. We executed two flights for seed dispersal on July 26, and three flights on July 27. Today, we hope to achieve three to four additional sorties,” he added.
Throughout the cloud-seeding experiment, Hendro indicated that the rainfall volume in the Lake Toba region has ranged from 0.5 to 50 mm. However, he acknowledged that cloud formation in the area remains suboptimal. “In the northern part of Lake Toba, rainfall has measured between 0.5 and 20 mm, while the southern region has seen 20 to 50 mm. Unfortunately, Samosir’s precipitation has been limited to 0.5 to 20 mm. These are the current rainfall outcomes,” Nugroho explained.
