Climate Overview
The climate in Pematangsiantar is cold. The average annual temperature is 1°C and approximately 159mm of precipitation falls per year. January is the wettest month, receiving around 27mm of rainfall. Pematangsiantar sits near the equator, so seasonal temperature differences are minimal throughout the year. Light snow can occur between January and August.
Temperature
Pematangsiantar has relatively stable temperatures year-round, staying within a 1°C range. January is the warmest month, though highs remain moderate at 2°C with a mean of 1°C. April is the coolest month, with minimum temperatures around 1°C and an average of 1°C. Daily temperature variation is modest, with an average difference of 1°C between highs and lows.
Precipitation
Pematangsiantar is a quite dry location, receiving approximately 159mm of precipitation annually, which averages out to around 13mm per month. The wettest month is January, averaging 27mm of rainfall. May and April also tend to see above-average precipitation. The driest month is September, with just 3mm. That's 24mm less than January, the wettest month. Rainfall is heavily concentrated in certain months, creating a distinct wet and dry season. Visitors should plan around these patterns, as the difference between peak and low months is dramatic. Light snowfall can occur between January and August, totalling around 32cm annually. January is the snowiest month with approximately 8cm.
Wind
Pematangsiantar is relatively calm, with an average annual wind speed of 5km/h. For context, sustained winds below 12km/h are generally light, while anything above 25km/h is considered strong. The windiest month is January, averaging 8km/h, though still comfortable for most outdoor activities. The calmest conditions occur in December, with average winds dropping to 3km/h, making it an ideal period for wind-sensitive activities. Wind speeds vary significantly across the year, with a 5km/h difference between the calmest and windiest months. This level of variation is worth factoring into travel plans.
Seasons
22 days until Autumn
It is currently summer in Pematangsiantar, which began on June 21, 2026. Pematangsiantar sits near the equator, so the traditional four-season cycle is less pronounced — temperatures remain relatively stable year-round. The warmest period peaks in January at around 2°C, while the coldest stretch bottoms out in April near 1°C. Autumn is next, beginning on September 23, 2026 — 22 days from now.
Spring
Temperatures range from 1 to 1°C. Rainfall is relatively light, with around 65mm over the season and a monthly average of 22mm. Winds are generally light, averaging 6km/h. Light layers work well as temperatures warm through the season — a great time to be outdoors.
Summer
Temperatures range from 1 to 1°C. Precipitation is minimal, with only around 27mm for the entire season. Winds are generally light, averaging 5km/h. Comfortable clothing with a light layer for cooler evenings is all you need.
Autumn
Temperatures range from 1 to 1°C. Precipitation is minimal, with only around 12mm for the entire season. Winds are generally light, averaging 4km/h. Layered clothing works best as temperatures gradually cool — enjoy the crisp air and changing scenery.
Winter
Temperatures range from 1 to 2°C. Rainfall is relatively light, with around 55mm over the season and a monthly average of 18mm. Expect around 11cm of snow accumulation during this period. Winds are generally light, averaging 6km/h. Warm winter clothing and waterproof boots are a must, and travel may be affected by snow.
Monthly Climate Data
The table below shows monthly climate averages for Pematangsiantar based on historical weather data. Min and max temperatures represent typical overnight lows and afternoon highs for each month, shown in degrees Celsius (°C). Precipitation is measured in millimetres (mm) and indicates the average total rainfall per month. Snow is measured in centimetres (cm) and reflects average monthly snowfall accumulation. Wind speed is the average sustained speed in kilometres per hour (km/h). All values are based on averages from over 10 years of historical weather data. The current month is highlighted for quick reference.
