Medan, the largest city of Sumatra and capital of North Sumatra, sits on a coastal plain in the northeast of the island, near the Strait of Malacca and backed by the Barisan mountains, at approximately 3.59°N, 98.67°E. It has a tropical rainforest climate (Köppen Af) — hot, humid and rainy year-round, with no true dry season — though the heaviest rain falls from October to January.

There is no summer in the temperate sense: temperatures stay warm and steady, with daytime highs around 31–33°C and warm, humid nights near 23–24°C, and consistently high humidity. Showers can occur in any month; the typical rhythm is a bright morning building to heavy afternoon and evening thunderstorms over the plain and the mountains inland.

Nor is there a true winter, but a relatively drier stretch comes around February and again around June and July, when rainfall eases and sunshine is more frequent. Even these months see substantial rain, so 'dry' is relative in northern Sumatra; the heaviest, most persistent rain falls from October to January, when flooding is common.

Medan is wet, receiving on the order of 2,000–2,200 mm of rain a year, with rain in every month and no true dry season, though the wettest stretch runs from October to January; nearby jungle regions such as Bukit Lawang are wetter still. Live rainfall, humidity, and pressure readings for the city are shown in the panels above.

Northern Sumatra receives rain in every month of the year, so Medan has no genuine dry season — a marked contrast with southern Sumatra and Java, where the monsoon carves the year cleanly in two. The Barisan mountains inland lift the moist air, feeding the rainforest and the heavy downpours that regularly flood the low coastal plain.

To follow any single measurement in Medan more closely, use our live instruments: the online barometer for atmospheric pressure, the thermometer for temperature, the hygrometer for humidity, the anemometer for wind speed, the wind vane for wind direction, and the rain gauge for rainfall.