by : Arif Setiawan
Notes based on weather monitoring equipment installed at the Owajawa SwaraOwa-Sokokembang education and conservation center, January 1, 2025-December 29, 2025.
[disclaimer: there are days when the device does not record data due to the power source being turned off from the device]
Throughout 2025, the Sokokembang forest experienced weather dynamics typical of humid tropical regions. Air temperatures ranged from 21°C to 31°C, with a heat index often higher than the actual temperature, indicating high humidity. This condition makes the air feel hotter, especially as humidity slows the evaporation of sweat. For forest animals and plants, this humidity requires further study to determine its impact. The Swaraowa team’s research on gibbons (gibbons) found a correlation between air humidity and the vocalizing behavior of Javan gibbons.
Rainfall shows an uneven pattern. Most days of the year are recorded without rain, indicating a long dry period. However, heavy rainfall does come in short, intense bursts. The highest rainfall peak occurred on December 2, reaching 63 mm in a single day—a crucial event that moistens the soil, fills rivers, and refreshes entire forest layers. In January, rain begins to return slowly after twenty dry days, with light to moderate intensity, peaking at around 14.4 mm before tapering off.
Rainfall records during the Petungkriyono landslide disaster on January 20, 2025
Several days before and after the landslide and during the landslide, electricity in Sokokembang often went out, so the equipment could not record daily climate data in Sokokembang.
Hydrological Implications
Increased runoff : Dry, hard soil has difficulty absorbing water quickly. Heavy rain in a short period tends to run off directly onto the surface, increasing the risk of local flooding or erosion.
Limited infiltration: Rainwater does not have time to seep into the ground, so groundwater reserves do not increase optimally.
River discharge fluctuations: Rivers can suddenly overflow during heavy rain, then recede quickly after the rain stops. The characteristics of rivers in the Petungkriyono Mountains: heavy rain in the upper reaches, while there is no rain in the middle and lower reaches/downstream, can cause unexpected flooding downstream.
Ecological Implications
Vegetation stress: Prolonged dry periods cause plants to experience water deficits. Sudden heavy rains don’t always immediately reverse the situation because roots need time to absorb the water.
Animal habitats: Arboreal animals (e.g. gibbons) may experience changes in activity patterns.
Forest productivity: Rainfall surges can encourage the growth of fungi, mosses, and understory plants, but also increase the risk of plant diseases due to sudden moisture surges.
Social & Conservation Implications
Landslide risk: Slopes that are dry and then suddenly saturated with water are more susceptible to landslides.
Community water availability: Long dry periods can reduce clean water supplies, while short periods of heavy rainfall are not enough to replenish reserves.
Flood and heavy rain warnings in the upper reaches of the river (around Petungkriyono sub-district), which are forwarded to villages along the river and downstream of the river which originates in Petungkriyono.
Conservation planning: This data is important for managing field activities, such as avoiding surveys during periods of potential extreme rainfall, or preparing community adaptation strategies for uneven climate patterns.
???? In short : prolonged dry periods weaken the soil’s and ecosystem’s absorption capacity, so sudden heavy rainfall causes more surface runoff than soil fertilization. The impacts can include local flooding, erosion, and disruption to the forest’s ecological cycle.
translated from original article here : https://swaraowa.blogspot.com/2025/12/karakteristik-iklim-harian-sokokembang.html