Mumbai sits on India's western coast on the Arabian Sea, on a cluster of former islands backed by the Western Ghats, just north of the Tropic of Cancer at approximately 19.08°N, 72.88°E. It has a tropical climate (Köppen Aw/Am, between savanna and monsoon) with a long, practically rainless dry season and a short but extraordinarily rainy monsoon. The sea keeps its temperature remarkably steady year-round, so instead of hot and cold seasons the year is defined by wet and dry.

The hot pre-monsoon period from March to May is warm and increasingly humid, with highs around 32–34°C, made to feel hotter by the coastal humidity. The real drama is the monsoon, which bursts over the city around 10 June and runs to late September: July is the wettest month, bringing weeks of near-continuous rain, dark skies and frequent waterlogging. The heavy downpours off the Arabian Sea, lifted by the Western Ghats, can flood large parts of the low-lying city.

The dry season from November to February is the most pleasant time, warm and comparatively less humid, with highs around 32–34°C and mild nights that can dip to 16–18°C in December and January — as cool as Mumbai ever gets. Skies are clear and rain is essentially absent. Even at its 'coolest', though, the city stays warm, since its coastal tropical setting keeps the temperature within a narrow band all year.

Mumbai is extremely wet in season, receiving on the order of 2,200–2,500 mm of rain a year — nearly all of it concentrated in the four monsoon months from June to September, with July alone often exceeding 800 mm. The suburbs see even more than the southern tip of the city. Outside the monsoon, months can pass with virtually no rain at all. Live rainfall, humidity, and pressure readings for the city are shown in the panels above.

The southwest monsoon is the overwhelming fact of Mumbai's weather, transforming the city for four intense months and regularly causing the flooding that paralysed it most catastrophically in July 2005. Uniquely among India's coastal metropolises, Mumbai rarely suffers direct cyclone strikes — the geography of the Arabian Sea usually steers storms away — though the humidity off the sea keeps the city feeling sticky through much of the year.

To follow any single measurement in Mumbai 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.