Climate of Melbourne

Melbourne, the state capital of Victoria and the second most populous city in Australia (most populous in urban area), has a temperate oceanic climate (Köppen climate classification Cfb), with warm summers and cool, damp winters. Melbourne is well known for its changeable weather conditions, mainly due to it being located on the boundary of hot inland areas and the cool southern ocean. This temperature differential is most pronounced in the spring and summer months and can cause strong cold fronts to form. These cold fronts can be responsible for varied forms of severe weather from gales to thunderstorms and hail, large temperature drops and heavy rain. Winters, while exceptionally dry by southern Victorian standards, are nonetheless drizzly and overcast. The lack of winter rainfall is owed to Melbourne's rain shadowed location between the Otway and Macedon Ranges, which block much of the rainfall arriving from the north and west.

Port Phillip is often warmer than the surrounding oceans or the land mass, particularly in spring and autumn; this can set up a "bay effect rain", where showers are intensified leeward of the bay. Relatively narrow streams of heavy showers can often affect the same places (usually the eastern suburbs) for an extended period, while the rest of Melbourne and surrounds stays dry. Overall, the area around Melbourne is, owing to its rain shadow, nonetheless significantly drier than average for southern Victoria. Within the city and surrounds, rainfall varies widely, from around 425 mm (17 in) at Little River to 1,250 mm (49 in) on the eastern fringe at Gembrook. Melbourne receives 48.6 clear days annually. Dewpoint temperatures in the summer range from 9.5 to 11.7 °C (49.1 to 53.1 °F).

Melbourne is also prone to isolated convective showers forming when a cold pool crosses the state, especially if there is considerable daytime heating. These showers are often heavy and can include hail, squalls, and significant drops in temperature, but they often pass through very quickly with a rapid clearing trend to sunny and relatively calm weather and the temperature rising back to what it was before the shower. This can occur in the space of minutes and can be repeated many times a day, giving Melbourne a reputation for having "four seasons in one day", a phrase that is part of local popular culture. The lowest temperature on record is −2.8 °C (27.0 °F), on 21 July 1869. The highest temperature recorded in Melbourne city was 46.4 °C (115.5 °F), on 7 February 2009. While snow is occasionally seen at higher elevations in the outskirts of the city, and dustings were observed in 2020, it has not been recorded in the Central Business District since 1986.

The sea temperature in Melbourne is warmer than the surrounding ocean during the summer months, and colder during the winter months. This is predominantly due to Port Phillip Bay being an enclosed and shallow bay that is largely protected from the ocean, resulting in greater temperature variation across seasons.