Melbourne has a temperate oceanic climate (Köppen Cfb) characterized by warm summers and cool winters, with highly changeable weather influenced by its position between hot inland regions and the cool Southern Ocean. This temperature contrast is strongest in spring and summer, often producing cold fronts that bring gales, thunderstorms, hail, heavy rain, and sudden temperature drops. Winters are relatively dry by southern Victorian standards but remain drizzly and overcast due to the city’s rain shadow between the Otway and Macedon Ranges.

Port Phillip Bay also affects local weather, particularly in spring and autumn. The “bay effect” can intensify showers on the leeward side of the bay, often impacting the eastern suburbs while other areas remain dry. Rainfall across Melbourne varies widely—from around 425 millimetres (16.7 in) at Little River to 1,250 millimetres (49 in) at Gembrook—and the city experiences approximately 48.6 clear days annually. Summer dew points range from 9.5 to 11.7 °C (49.1 to 53.1 °F).

Melbourne is known for sudden convective showers that can include hail and squalls, often passing quickly and returning to sunny conditions within minutes. This rapid variability has given rise to the popular local saying that Melbourne has “four seasons in one day.” The city’s extreme temperatures range from a low of −2.8 °C (27.0 °F) recorded on 21 July 1869, to a high of 46.4 °C (115.5 °F) on 7 February 2009. Snow is rare in the outskirts and has not fallen in the CBD since 1986.

Sea temperatures in Melbourne reflect the seasonal contrast of Port Phillip Bay, which warms more than the surrounding ocean in summer and cools more in winter due to its shallow, enclosed nature. These climatic features create a city known for both rapid weather changes and a diverse range of seasonal conditions, contributing to Melbourne’s unique character and lifestyle.