Weather in Cairns in December

A hard month. December asks something of you. Go in knowing what. You should expect rain on 17 days of the month, which is more days wet than dry.

December ranks 12 of 12 — near the bottom of Cairns's year. August is the month that works, and the swing between the two is 49 points, which is a different holiday rather than a slightly better one.

Rain on 17 days, 5 of them heavy. Enough to need a plan B, not enough to need a plan around it. Pack for 32.6 °C days and 24.8 °C nights; the spread matters more here than any single number.

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 40.3 °C and the coldest night fell to 20.7 °C, and the wettest single day dropped 105 mm — roughly 59% of the month's rain in one day.

December is moderately variable: 14 mm in the driest year against 513 mm in the wettest, around an average of 179 mm. Roughly two Decembers in three land near that average, and the third does something else entirely.

Wind is light at 5.8 km/h, so the temperature on the page is close to the temperature on your skin, and humidity runs at 77%, high enough to notice on the warm days without dominating them.

How December sits in the year

Temperatures hold steady either side: 32.1 °C in November, 32.6 here, 30.9 in January. Nothing about the timing within the month matters much. Rain is the thing that moves: January brings 7 days more of it, so the earlier half of a flexible trip is the safer half.

Daylight in December

December is at or near the longest days of Cairns's year: 13.1 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 28.5 °C in December — warm enough that the water offers no relief from the heat. The sea peaks at 29.2 °C in February and bottoms out at 24.7 °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

Off season. The genuine off season: cheapest by a distance, with the caveat that some tours and restaurants close entirely.

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

December in Cairns versus nearby

If Cairns is one option among several, the nearby comparison is worth making. Port Douglas is a better bet in December — 2.2 °C cooler, the same number of rain days. Townsville is a better bet in December — within a degree on temperature, 7 days less rain.

So: December is a compromise. August is 49 points better and is what Cairns is actually like at its best — worth moving the trip for if that is possible, and worth adjusting expectations for if it is not.

Every month in Cairns

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