Clickable chart
Great Barrier Reef time to visit, month by month
Light through the year
Twelve months at Cairns
Choose a month to compare sunset, day length and the usual warmth and rain at Cairns, with what the sources say about the Reef that month.
Sunset
Jan
January has 13 wet days and 380 mm of rain on the NOAA averages.1
Feb
February is the wettest month, with 480 mm of rain on 14 wet days.1
Jun
Humpback whales are in the World Heritage Area from May to September.2
Jul
July has the lowest average daily low, 17.2 °C, and 4 wet days.1
Aug
August is the driest month, with 27 mm of rain on 3 wet days.1
Oct
Corals usually spawn after the full moons of October, November and December.3
Dec
December has 172 mm of rain on 9 wet days, with highs of 31.8 °C.1
Sunset is worked out for the 15th of each month on Queensland time. Day length is for Cairns; temperatures come from the NOAA station at Cairns Aero, 6.1 km away, and rainfall from Cairns Post Office, 1.7 km away, 1991 to 2020. Neither is a reading taken on the reef.
Rain, sun and wind at Cairns, the Reef Authority's heat and health reports, and the whale and spawning calendar, set against the months a reef day is actually run.
Editorial team, greatbarrierreeftour.quest · Updated November 7, 2026 · 7 mins to read
In brief
- Driest runJune to October brings 27 to 58 mm of rain a month at Cairns.1,1,1
- Wettest runFebruary averages 480 mm and 14 wet days.1
- WhalesHumpbacks arrive from May to September.2
- SpawningCorals usually spawn after the October, November and December full moons.3
- Heat riskSummer carries a heightened risk for the Reef.4
When the weather is kindest for a reef day
The Great Barrier Reef time to visit question has a fairly clear answer for a reef day from Cairns, because the year splits in a clear way. The cooler, drier months run from June to October: the NOAA averages for Cairns give 43 mm of rain in June, 35 mm in July, 27 mm in August, 29 mm in September and 58 mm in October, with between 3 and 4 wet days a month from July to October.1,1,1,1,1 These are Cairns figures from NOAA's town and airport stations, not readings taken on the reef.
The wet months are the opposite. January brings 380 mm, February 480 mm and March 349 mm, on 13, 14 and 12 wet days.1,1,1 The long-term Bureau of Meteorology figures tell the same story at the airport: rain of 1 mm or more falls on a mean of 16.1 days in February and 4.9 days in August.5 Anyone asking about the worst time to visit the Great Barrier Reef will find that the rain data points at the first quarter of the year.
Temperatures swing less than rainfall does. The average daily high is 31.8 °C in December and 26.2 °C in July, and the average low falls to 17.2 °C in July.1,1 A July reef day is cooler on deck, so pack warm layers for the run out even in the tropics. The wettest months are also the hottest, with a 24 °C average low in January and 24.1 °C in February.1,1
Sun, cloud and wind through the year
The Cairns airport records a mean of 6.2 hours of daily sunshine in February and 8.8 hours in October,8 and a mean of 2.5 clear days in February against 12.4 in September.9 Cloudy days run the other way, with 17.4 in February and 5.4 in October.10 Clear skies put more light on the coral, which helps for photographs, and the drier half of the year offers them more often.
Wind is the other half of the picture. The mean 3 pm wind speed at the airport is 14.6 km/h in February and 20.5 km/h in September,11 while the mean 9 am speed rises from 8.8 km/h in January to 15.9 km/h in June.12 These are land readings at Cairns Aero, a station that opened in 1941 and sits at 2 metres elevation,13 and they describe the coast, not the open water.
The sea itself is a job for the marine forecast. One coral cay cruise listing points guests with weather concerns to the Bureau of Meteorology for a 4-day marine weather forecast, and the superyacht listing says the day depends on the weather. This site's listing adds that bad weather can limit the day to a single reef, with the skipper deciding on the way out. Expect the plan to flex, and book with a cancellation window in hand.
Climate
Cairns by month: rain, wet days and warmth
- Jan11.0 h
- Feb11.3 h
- Mar11.8 h
- Apr12.3 h
- May12.7 h
- Jun12.9 h
- Jul12.8 h
- Aug12.5 h
- Sep12.0 h
- Oct11.5 h
- Nov11.1 h
- Dec10.9 h
Counts of sunless mid-month hours and of days with at least 2.5 mm of precipitation, from NOAA station Cairns Post Office and Cairns Aero, 1991 to 2020.1
Heat, bleaching and the reef health reports
Summer is the Reef's high-risk season, when extreme heat brings the threat of marine heatwaves and coral bleaching.4 Corals in shallow water are the most at risk of bleaching, where the water warms up quickly and sunlight is intense,14 and bleached corals can recover once conditions return to normal.15 A month that is good on weather alone is not automatically a good month for coral.
From May to November the Reef Authority issues regular reef health reports built from forecasts, sea-temperature heat maps, surveys in the water and from the air, and citizen science.7 Its summer 2025-26 snapshot reports a regional bleaching event in the Northern region, with small, localised amounts of bleaching in the Far Northern, Central and Southern regions,16 and it covers coral only, not the health of other habitats or species.17 Read the current report before you book rather than relying on a past season's reputation.
The Authority warns that stories that fixate on how much of the Reef has died tend to oversimplify, since there are more than 3000 reefs and each one is a dynamic system.18 Not all corals on one reef get the same amount of heat stress either.19 A sensible way to use that is to judge a reef day by what is reported for the area you will actually visit, and to ask your operator which reefs the crew expect to choose that week.
Pick your month
Which month suits your priority?
Choose the line closest to what matters most and read the answer beside it.
If I want the driest weather
June to October
If I want clear skies for photographs
September to October
There are 12.4 clear days in September and only 5.4 cloudy days in October.9,10
If I want to see whales
May to September
Humpbacks arrive in that window.2
If I want to see coral spawning
October to December
Spawning follows those full moons.3
If I want the lowest wind
January or February
The mean 9 am wind is 8.8 km/h in January.12
A wildlife calendar: whales, spawning and turtles
Humpback whales travel up from Antarctic waters between May and September to calve in the Great Barrier Reef World Heritage Area and build strength over winter.2 A 40-minute scenic flight over the outer edges of the Reef notes that humpback whales may be spotted in July and August. Whale watching and swimming with whales follow that winter journey of the animals to the Reef.21
Minke whales have their own window. The Authority says recent research points to the Ribbon Reefs north of Cairns as a key area for minke whales, especially around May to July, when dive vessels meet them regularly,6 and one liveaboard operator gives its minke season as June to July.22 A Port Douglas catamaran day offers dwarf minke whale swims in season with a licensed vessel.
Coral spawning is the reef's biggest annual event. Corals usually spawn in the nights that follow the full moons of October, November and December, with the exact timing depending on the reef, typically one to six nights later.3,23 It usually happens at night.24 Sunlover notes that spawning happens at night and invites guests out the next day to look for it floating at the surface, by boat or helicopter,25 and Tusa Reef Tours lists coral spawning charters among its trips.26
The reef calendar
A year of reef events in order
January to March
The wettest months
Rain is 380 mm, 480 mm and 349 mm over those 3 months at Cairns.1,1,1
Summer
The heat watch
Summer carries a heightened risk for the Reef.4
May to September
Humpback whales
Humpbacks come to the World Heritage Area from Antarctic waters.2
May to July
Minke whales
Dive vessels regularly meet minke whales around the Ribbon Reefs.6
May to November
The reef reports
The Authority issues regular reef health reports.7
October to December
Coral spawning
Corals usually spawn on the nights after those full moons.3
Month by month for planning
November and December are the build-up. Rain is 87 mm in November and 172 mm in December, on 6 and 9 wet days, with average highs of 31.1 °C and 31.8 °C.1,1 Sun above the horizon at mid-month is 12.9 hours in November and 13.1 hours in December.1,1 The months also overlap with the spawning nights and the start of the heightened heat risk, so the reef calendar and the weather calendar pull in different directions.
April and May are the drying tail of the wet season. Rain falls at 179 mm in April and 82 mm in May, on 11 and 7 wet days.1,1 The average daily high eases from 29.6 °C to 28 °C between them.1,1 May is also when the humpback whales begin to arrive, which makes it an interesting shoulder month for travellers who want both calmer rain and a chance of whales.
Through the middle of the year the days are shortest: sun above the horizon at mid-month is 11.1 hours in June and 11.2 hours in July, against 13 hours in January.1,1,1 A reef cruise is a daylight activity, so the shorter days matter less than the early check-in time of 7 AM to 7:45 AM for this site's 8 AM departure.
Video
Swimming with whales on the Great Barrier Reef
Expedition Drenched on YouTube · The video waits until you tap play to load.
Summer is always a period of heightened risk for the Reef, as extreme hot weather brings the threat of marine heatwaves and coral bleaching.
Timing it right
A timing checklist before you book
Check first4
Planning around weather and cancellations
The Reef Authority says everyone can visit the Marine Park throughout the year.27 There is no closed season for a reef cruise, but conditions and sea state change, and the cancellation rules matter more in the wetter months. This site's listing offers free cancellation up to 24 hours before for a full refund, and reserve now and pay later.
The wearable side of timing is easy to overlook. A lycra or wet suit protects against sunburn and stings from jellyfish,20 and Reef Magic says its lycra suits are useful in season for reducing the risk of jellyfish stings.28 The Queensland Government says marine stingers are present in tropical Queensland all year, with a higher risk from November to May,29 so ask the operator what is in force on your date.
The best month to visit the Great Barrier Reef depends on whether you rank dry weather, whales or spawning first. If you can choose, treat the weather data as one input and the reef report as another. Dry, clear months make for easier days on deck and better light, while the reef health reports and the whale and spawning calendars decide what you might see below the surface. A flexible traveller can plan around all three.
FAQ
The short answers to your questions.
What is the best month for a Cairns reef day?
Is there a month to avoid entirely?
When can I see whales on the Reef?
When does coral spawn?
Does heat affect the Reef in summer?
Summer brings the threat of marine heatwaves and coral bleaching.4
Where can I read current reef conditions?
It issues regular reports from May to November.7
How windy does it get at Cairns?
The mean 3 pm wind speed at the airport runs from 14.6 km/h in February to 20.5 km/h in September.11
Can bad weather cancel the day?
One listing says the activity depends on the weather, and this site's listing notes the skipper may limit the day to a single reef.
Sources
- NOAA · Global Summary of the Month, Station Cairns Post Office and Cairns Aero (NOAA GHCN ASN00031010 / ASN00031011), 1991 to 2020 ↩
- Great Barrier Reef Marine Park Authority · Whales and dolphins ↩
- Great Barrier Reef Marine Park Authority · Coral spawning 101 ↩
- Great Barrier Reef Marine Park Authority · Sea temperature ↩
- Bureau of Meteorology · Climate statistics for Australian locations: Cairns Aero (031011) ↩
- Great Barrier Reef Marine Park Authority · Whales and dolphins ↩
- Great Barrier Reef Marine Park Authority · Reef snapshot ↩
- Bureau of Meteorology · Climate statistics for Australian locations: Cairns Aero (031011) ↩
- Bureau of Meteorology · Climate statistics for Australian locations: Cairns Aero (031011) ↩
- Bureau of Meteorology · Climate statistics for Australian locations: Cairns Aero (031011) ↩
- Bureau of Meteorology · Climate statistics for Australian locations: Cairns Aero (031011) ↩
- Bureau of Meteorology · Climate statistics for Australian locations: Cairns Aero (031011) ↩
- Bureau of Meteorology · Climate statistics for Australian locations: Cairns Aero (031011) ↩
- Great Barrier Reef Marine Park Authority · Coral bleaching ↩
- Great Barrier Reef Marine Park Authority · Coral bleaching ↩
- Great Barrier Reef Marine Park Authority · Reef snapshot ↩
- Great Barrier Reef Marine Park Authority · Reef snapshot ↩
- Great Barrier Reef Marine Park Authority · Coral bleaching ↩
- Great Barrier Reef Marine Park Authority · Coral bleaching ↩
- Great Barrier Reef Marine Park Authority · Responsible reef practices ↩
- Great Barrier Reef Marine Park Authority · Ways to visit ↩
- Mike Ball Dive Expeditions · Liveaboard diving Cairns ↩
- Great Barrier Reef Marine Park Authority · Coral spawning 101 ↩
- Great Barrier Reef Marine Park Authority · Coral spawning 101 ↩
- Sunlover Reef Cruises · Great Barrier Reef Tours from Cairns ↩
- Tusa Reef Tours · Half-day snorkel tour ↩
- Great Barrier Reef Marine Park Authority · Ways to visit ↩
- Reef Magic Cruises · Reef Magic ↩
- Queensland Government (qld.gov.au) · Dangerous marine life ↩
- Sunlover Reef Cruises (operator official site) · Reef weather
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