Weather in Adelaide in December

Prime time. December is about as good as Adelaide gets. Highs average 27.9 °C, lows 14.6 °C, and rain falls on 4 days — nothing in the month is working against you.

December ranks 4 of 12 in Adelaide: past the worst of the year but short of March, which is the month to book if the dates are open.

Rain falls on only 4 days, so an itinerary with no wet-weather fallback is a reasonable risk. 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: 5 days clear 35 °C, so a serious heatwave is normal rather than notable. Across the twenty years measured, the hottest December day reached 45.2 °C and the coldest night fell to 8.8 °C, and the wettest single day dropped 26 mm — roughly 113% of the month's rain in one day.

This is the volatile part. December rainfall has ranged from 0 mm to 80 mm across the twenty years measured — a 80 mm spread around an average of 23 mm. The average is real but almost no individual December looks like it, so treat the figure as the middle of a wide range rather than a forecast.

Wind is light at 11.4 km/h, so the temperature on the page is close to the temperature on your skin, and humidity is unremarkable at 53%.

How December sits in the year

The month is on the way up: 2.1 °C warmer than November, and January adds another 2.7 °C. Late in the month feels noticeably different from the start of it, which is worth knowing if the trip is short.

Daylight in December

December is at or near the longest days of Adelaide's year: 14.5 hours of daylight, holding steady all month. Evenings are the real gain — dinner outdoors still happens in full light.

An inland climate

Despite being inland, the year stays fairly even: 23.5 °C between the year's warmest afternoons and coldest nights.

How busy it gets

Peak season. Expect the highest prices of the year and to be booking well ahead. If the dates are flexible, September is the trade worth considering — 13 points weaker on weather, and materially quieter.

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

December in Adelaide versus nearby

If Adelaide is one option among several, the nearby comparison is worth making. Gawler is the weaker option in December — 2.7 °C warmer, the same number of rain days. Whyalla is close enough to be a coin toss — within a degree on temperature, 1 day less rain.

So: December is effectively as good as it gets here — 3 points behind March, which is inside the margin where the weather stops being the deciding factor and price starts being it.

Every month in Adelaide

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