Cairns · Month comparison

September vs July

July ranks #1 overall vs September at #5. Peak season — the best reef conditions of the year with Australian and international visitors at maximum

Great Barrier Reef in September with excellent conditions

September

#5 of 12 months

Best match

Excellent shoulder season — top reef conditions continue with summer holiday crowds gone

  • ↑Good reef conditions still; end of humpback whale season with last sightings in September
  • ↑Warm 25–30°C but not yet humid; perfect for diving and Daintree rainforest exploring
Great Barrier Reef Outer Reef in peak July conditions with coral and fish

July

#1 of 12 months

Best match

Peak season — the best reef conditions of the year with Australian and international visitors at maximum

  • ↑The most reliably excellent conditions: clear skies, flat seas and 30m+ reef visibility
  • ↑Dwarf minke whale encounters (June-July only) unique to the northern Great Barrier Reef
FactorSeptemberJuly
Weather score
8
9
Value score
5
4
Crowd score
6
8
Events score
5
5
Atmosphere
8
8
Avg high temp28°C25°C
Monthly rain38mm23mm
Daily sunshine10.5hrs11hrs

September trade-offs

  • ↓Humidity beginning to build toward wet season
  • ↓First signs of marine stinger season beginning by late September

July trade-offs

  • ↓Maximum crowds; popular reef pontoons at Agincourt can have 200+ visitors simultaneously
  • ↓July school holiday peak: every liveaboard and dive operator fully booked, prices at maximum
See all 12 months for Cairns →September in detail →July in detail →
Scores compare months within Cairns. Climate data: Open Meteo ERA5 30-year normals (1991–2020). Methodology →