Weather in Sydney in December

How December compares

December is the 3rd warmest month of the year in Sydney and ranks 40th of 134 destinations we compare for December - see where else is hot in December. Against London's average high of 7.7°C in December, Sydney is 16.7°C warmer by day and 15.0°C warmer at night.

Daytime and night-time in December

The typical December day in Sydney peaks at 24.4°C, but that is an average: the warmest 10% of days reach 29.0°C or more. Roughly 1 in 3 days top 25°C and 1 in 14 pass 30°C. Nights average 17.7°C; one night in ten drops to 15.2°C or lower, so pack a layer for evenings. Between 1991 and 2020 the hottest December day here reached 40.5°C (2019-12-31) and the coldest night 11.1°C (1995-12-26).

Rain in December

Wet (more than 8 rainy days): about 9 days with 1 mm or more, 56 mm in total. Year to year it varies a lot - the wettest December was 2014 with 124 mm, the driest 2019 with 16 mm. Humidity averages 71%.

Sea temperature in December

The sea averages 21.0°C - bracing (18-22°c). Depending on the year it ranges from 20.1°C to 21.8°C. For the warmest sea here, come in February (23.0°C).

Sunshine and daylight

Around 6.3 hours of sunshine a day (estimated from cloud cover), 14.2 hours of daylight: the sun rises about 05:39 and sets about 20:02 local time in mid-December. Average cloud cover is 56%.

Is December a good time to visit Sydney?

Yes - it is one of the better months: warm days, manageable rain. The best months for Sydney on our scoring are December, January, February; months averaging 25°C or more: Jan, Feb.

Warm days, with hotter spells possible

Pack mainly for warmth, but leave room for a light layer. The warmest days reach 29°C or more, while 30°C heat occurs on just 7% of days: possible, but not the everyday expectation. Humidity of 71% can make warmer afternoons feel close, so keep strenuous outdoor plans flexible and take shade breaks when needed. Evenings are generally mild, though cooler nights can fall to around 15°C or below, making a jumper useful if you are staying out. December is among Sydney's warmest months, but the averages point to a trip that is usually warm rather than consistently hot. That balance should suit travellers who dislike sustained heat.

Keep outdoor plans flexible

Rain is a meaningful catch in December, with about 9 rainy days across the month. Allow some flexibility rather than assuming every day will suit a full outdoor schedule; that figure does not mean each wet day is a washout. There is plenty of daylight to work with, around 14.2 hours, but average sunshine is only about 6.3 hours, so long days do not translate into uninterrupted sun. Pack a light waterproof alongside sun protection. For swimming, expect the sea to feel fresh on entry rather than bath-warm. If warm water is central to your holiday, Sydney in December is a less convincing fit than its daytime temperatures might suggest.