Semarang Air Quality Index (AQI)

Loading live AQI data...

Loading historical AQI trends...

Semarang, the capital of Central Java province in Indonesia, occupies a distinctive coastal position on the northern Java Sea coastline, approximately 400 kilometers east of Jakarta. This port city straddles a dramatic urban–rural gradient, with its northern low-lying coastal plains merging into the southern uplands of the Kendeng Mountains, creating an elevation range from sea level to about 340 meters in the southern suburbs. Semarang's geography profoundly shapes its air quality through multiple mechanisms. The city sits within Java's densely populated northern corridor, part of an industrial belt extending from Jakarta to Surabaya, with manufacturing zones concentrated along the coast and transportation arteries. Surrounding landscapes include rice paddies and agricultural zones to the south and east, where seasonal burning contributes particulate matter. Proximity to the Java Sea provides some maritime ventilation, but this is often limited by the city's bowl-like topography, where southern hills trap pollutants, especially during periods of atmospheric stability. The urban heat island effect intensifies local pollution retention, while the Semarang-Demak toll road corridor channels vehicle emissions through the metropolitan area. This combination of industrial activity, transportation networks, topographical confinement, and agricultural influences creates a complex air quality scenario where both local emissions and regional haze from Sumatra or Kalimantan during dry seasons can converge.

Semarang's air quality follows distinct seasonal patterns driven by Indonesia's monsoon climate, though located near the equator where traditional four-season divisions are less pronounced. During the northwest monsoon from November to March, increased rainfall typically washes pollutants from the air, resulting in cleaner conditions ideal for outdoor activities, with January and February often being the most favourable months. The transitional periods of April-May and September-October see variable conditions as monsoon winds shift, sometimes allowing pollution accumulation during calm intervals. The critical period occurs during the southeast monsoon from June to August, when drier conditions prevail. This dry season brings elevated pollution levels due to reduced rainfall, increased agricultural and land-clearing fires in surrounding regions, and more frequent temperature inversions that trap pollutants in Semarang's topographical basin. July and August typically represent peak pollution months when sensitive groups—including those with respiratory conditions, children, and the elderly—should limit prolonged outdoor exposure, especially during morning hours when inversion layers are strongest. Throughout the year, sea breezes from the Java Sea provide some daytime ventilation, but these often weaken at night, allowing pollutants to accumulate. The city occasionally experiences transboundary haze from Sumatra or Kalimantan during extended dry periods, further degrading air quality beyond local emissions.