Great Barrier Reef Weather.

Cairns weather
Cairns Lagoon

If you are not from Australia the weather patterns and terms can be a little confusing.

North Queensland has a tropical weather pattern that is consistent over the years.

Generally it can be seen as having two seasons, a wet season and a dry season.

The rains start to increase in December, are at their heaviest from January to March tampering off in April. May to November are the dry months.

While you may expect the wet season to be the coolest, it is in fact the hottest.

If you are not totally confused yet, lets add one more. You will also hear people refer to the four seasons. Australia covers different weather zones and a portion of the country, the most populated, is in a temperate zone.

Great Barrier Reef weather
Reef Accommodation

The weather patterns here are similar as you will find in Europe and the United States, except they are reversed. The seasons in the temperate zone are:

Winter: June to August

Spring: September to November

Summer: December to February

Autumn: March to May

This will help explain why the wet months is also the hottest, it in the summer, if their were four seasons.

Tropical Cyclones may form in the summer months over the ocean.

While scientist would disagree, a Cyclone, typhoon and a hurricane are all the same.

There are some minor differences and they develop in different oceans but the effects are the same.

The cyclone season generally lasts from November to April.

Cairns is in the band for cyclones but the majority of them happen further north.

Local dive operators express that on average, one week of diving is effected every two years.

Cairns Weather Chart

Month Max Temp in °C Min Temp in °C Water Temp in °C  Rainfall MM
January 31.6 23.6 29 405
February 31.3 23.7 28 434
March 30.7 23.0 27 424
April 29.4 21.5 26 197
May 27.9 19.5 26 99
June 26.3 17.6 24 49
July 25.9 17.0 24 30
August 26.7 17.5 22 27
September 27.8 18.6 23 35
October 29.4 20.5 26 38
November 30.6 22.2 26 89
December 31.4 23.3 27 175

10 year average

 

When to Scuba dive

If you look at the monthly average temperatures, you will see that the day time temperatures stay very comfortable.

You might want to add a sweater or sweat shirt but more than that is really not needed.

You might need a slightly thicker wet suit in August than in January, but no need to bring out a dry suit.

 

The “wet” season brings warmer water. Also, the rain patterns are such that more rainfall falls over land that out on the outer reefs.

The distance between most of the dive sites and the coast are great enough that the run off from the rain does not affect the visibility on the reef.

 

The dry season has its advantages as well, the day time temperatures are more comfortable.

Great Barrier Reef weather
Humpback Whale

One major advantage is migration patterns. Dwarf Minke Whales,

Whale sharks and to a lesser extend humpback whales leave the cold winter waters of the Antarctic and move up the Australian coast.

The area north of Cairns is one of the destinations that sees these marine animals every year.