Semarang, the capital of Central Java, sits on the island's northern coast on the Java Sea, on a low coastal plain that rises steeply into hills behind the city, at approximately -6.97°S, 110.42°E. It has a tropical monsoon climate (Köppen Am) — hot and humid year-round — with a distinct wet season from November to March and a dry season from May to September.

There is no summer in the temperate sense: temperatures stay hot and steady, with daytime highs around 31–33°C and warm, humid nights, tempered a little by sea breezes off the Java Sea. The wet season, from November to March, brings heavy afternoon and evening downpours and thunderstorms, high humidity and frequent flooding on the low coastal plain.

There is no true winter, but the dry season from May to September brings hot, sunny, drier days with much less rain and slightly lower humidity. This bright, dry stretch is the most comfortable time of year, though the inland heat can be intense; the hills behind the city stay noticeably cooler than the sweltering coast.

Semarang receives on the order of 2,600–2,900 mm of rain a year, concentrated in the wet season from December to March, while June to September sees very little; the wet-season downpours regularly flood the low-lying old city. Live rainfall, humidity, and pressure readings for the city are shown in the panels above.

Semarang faces a compounding flood problem: torrential wet-season rain from the hills meets a coastline that is subsiding rapidly as groundwater is extracted, so parts of the old lower city now sit below the tide line and flood both from rain and from the sea — one of the most acute cases of coastal subsidence in Indonesia.

To follow any single measurement in Semarang 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.