Weather in Sydney in December

Prime time. If you get to pick your dates, December is the one. Highs average 24.3 °C, lows 18.7 °C, and rain falls on 11 days — nothing in the month is working against you.

Sydney barely has seasons. December scores 80 out of 100 against a best of 86 in September — a gap small enough that the month you choose matters far less here than the week you choose.

Rain on 11 days, 2 of them heavy. Enough to need a plan B, not enough to need a plan around it. Nothing specialised needed — this is the month you pack for the trip rather than for the weather.

What the averages hide

Averages flatten a month, and this one hides a few things: the day barely swings — 5.6 °C between the overnight low and the afternoon high. Across the twenty years measured, the hottest December day reached 37.4 °C and the coldest night fell to 13.5 °C, and the wettest single day dropped 51 mm — roughly 71% of the month's rain in one day.

December is moderately variable: 2 mm in the driest year against 143 mm in the wettest, around an average of 72 mm. Roughly two Decembers in three land near that average, and the third does something else entirely.

Wind is light at 11.3 km/h, so the temperature on the page is close to the temperature on your skin, and humidity is unremarkable at 73%.

How December sits in the year

Temperatures hold steady either side: 22.9 °C in November, 24.3 here, 25.7 in January. Nothing about the timing within the month matters much.

Daylight in December

December is at or near the longest days of Sydney's year: 14.4 hours of daylight, holding steady all month. Evenings are the real gain — dinner outdoors still happens in full light.

Sea temperature

The sea sits at about 22 °C in December — comfortable for a proper swim. The sea peaks at 24.1 °C in February and bottoms out at 18.7 °C — water lags the air by a month or two, which is why the best swimming often comes after the best weather.

How busy it gets

Busy. Popular without being frantic; book the things you care about, improvise the rest.

Crowd levels are estimated from climate desirability and school-holiday calendars, not from visitor numbers.

December in Sydney versus nearby

If Sydney is one option among several, the nearby comparison is worth making. Central Coast is close enough to be a coin toss — 3.3 °C warmer, the same number of rain days. Katoomba is close enough to be a coin toss — within a degree on temperature, the same number of rain days.

So: December is effectively as good as it gets here — 6 points behind September, which is inside the margin where the weather stops being the deciding factor and price starts being it.

Every month in Sydney

See all twelve months in Sydney, or where else to go in December.