Queensland month by month, at a glance
Figures for Cairns, 1991-2020 series. It rains far less in the south of the state and the winter is cooler. Hover over each month.
In Cairns the highest mean maximum of the year is 31.7 °C, in January, and the lowest 26.2 °C, in July. The minima run from 17.2 to 24.0. That is a six-degree spread in the maximum: enough to feel the winter, not enough to decide a trip. The variable that does decide is the water: how much falls, and what is inside it.
The key moments at a glance
475.5 mm in February and only 175.2 hours of sun, the annual low. It is also cyclone season, which runs from November to May, and the tropical coast's water is closed by the stingers.
Rain drops from 42.6 to 26.6 mm and afternoon humidity from 61 to 56 per cent. July is the coolest month, with a mean maximum of 26.2 °C and the sea at 23.8 °C.
28.4 and 63.4 mm of rain, with 270.0 and 279.0 hours of sun. The humpbacks are still on the coast, the stingers have not returned and the water is clear.
85.1 mm and the heat returning, but this is the month of coral spawning, in the nights after the full moon. It is also when the stinger nets go back in.
01 Six degrees in twelve months
The figures are for Cairns, 1991-2020 series, and they describe the tropical north. The state is enormous and the south behaves differently: in Brisbane the winter is clearly cooler and it rains far less. But along the strip most people go to see, from Bundaberg northwards, the pattern is the one these numbers give.
What does change with the seasons is afternoon humidity: 71 per cent in February against 55 in September. Thirty degrees at 55 per cent is a comfortable day for walking; thirty degrees at 71 per cent is something else. When someone says August is 'less hot', they are describing the hygrometer.
Rainfall moves on a completely different scale. February takes 475.5 millimetres; August, 26.6. Almost eighteen to one. The sunshine hours follow: 175.2 in February, 279.0 in October.
02 For half the year the sea is closed
From November to May there are dangerous jellyfish along Queensland's tropical coast. They come in two distinct groups. The box jellyfish is large and transparent, with a pale blue, cube-shaped bell and tentacles that can reach three metres. The Irukandji is the opposite: a bell of about five millimetres and tentacles up to a metre long.
The Irukandji is the one that forces a change of plan. Its sting begins as a minor skin irritation and, between five and forty minutes later, brings on generalised muscular pain, headache, vomiting and sweating. And it is small enough to pass through the mesh of the nets.
So from November to May the northern beaches are fenced with stinger nets and a lycra suit is recommended even inside the netted area. In practice, for those seven months the tropical coast is not a beach you walk into casually.
There is one important exception, and it changes the whole trip: the outer reef. Conditions there — deeper, more open water — are unfavourable to these animals, and both the box jellyfish and the Irukandji are very rare at the sites where dive and snorkel boats moor. In other words, you can still go to the reef in stinger season. What you lose is the beach.
03 The dry season and the trade wind
From June to October the north changes regime. June leaves 42.6 mm, July 35.5, August 26.6 and September 28.4, the lowest of the year. Sunshine hours rise to October's 279.0 and afternoon humidity falls to 55 per cent.
With the dry season comes the south-east trade, which blows steadily through those months and has two faces. On land it orders the day and takes the mugginess out of it. At sea it raises a short chop that can spoil a reef trip, especially in July and August, the windiest months.
The water changes too: the sea goes from 29.4 °C in January to 23.8 in July. Still warm by European standards, but a full day of snorkelling in July calls for a thin wetsuit.
04 The animals' calendar
This is where the calendar stops being meteorological. Between June and July dwarf minke whales pass reliably through the Ribbon Reefs, north of Cairns, and approach the boats of their own accord. It is a short, very localised appointment: two months and one particular stretch of reef.
The humpbacks come later. In Hervey Bay, halfway down the coast, the season runs from July to October with the bulk between August and September. The bay works as a resting place on the way back south, which is why the sightings are of animals at a standstill rather than passing through.
The turtles work the opposite half of the year. At Mon Repos, next to Bundaberg, the females come ashore to nest from November to January and the hatchlings emerge from December to March. These are guided night visits in groups: the animal sets the timetable, not the brochure.
And there is one date that appears on no printed calendar: coral spawning. It happens in the nights following the November full moon, lasts a few hours and shifts every year. It cannot be booked in advance with any guarantee.
05 What to choose, and one hour worth knowing
If the aim is reliable weather and clear water, the answer is September and October. Rain at its lowest, sun at its highest, the whales still there and the stingers not yet back. It is the one window that makes beach and reef compatible.
If the trip is about diving and whales, July and August work just as well, with two tolls: they coincide with the Australian holidays and the trade wind blows harder, so the odd boat trip may shift or be cancelled.
And if you can only travel between January and March, it is not lost, but the plan changes: reef yes, beach no, and expect the afternoon to be wet. It is also cyclone season, November to May. That does not mean there will be one; it means a warning can wipe three days of boats off the schedule.
One practical detail catches a lot of people out: Queensland does not put its clocks forward in summer. When Sydney and Melbourne change, Queensland stays where it was and ends up sixty minutes behind. If you are connecting flights or booking a departure from another state, check it twice.
