Best Time to Dive in Cairns
The pull is the outer Great Barrier Reef. That does not change through the year, so go when the weather is best: July to November. The full season runs June to November.
- Best time
- Jul–Nov
- Water
- 25–30 °C
- Visibility
- 15–30 m
- Season runs
- Jun–Nov
- Dived from
- liveaboard and day boat
- Tidal range
- 1.0–2.3 m
- Species logged
- 22
Worth knowing: 10 days a month of heavy rain.
Where it is
111 km across · coastline from Natural Earth 10m
Diving in Cairns — monthly breakdown
A year of scuba diving conditions at a glance. Hover a month to isolate it.
| January | February | March | April | May | June | July | August | September | October | November | December | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Conditions | Poor | Poor | Poor | Poor | Moderate | Good | Good | Good | Good | Excellent | Excellent | Moderate |
| Water temp (°C) | 29 | 30 | 29 | 28 | 27 | 26 | 25 | 25 | 26 | 27 | 28 | 29 |
| Visibility (m) | 20–30 | 20–30 | 15–25 | 20–30 | 15–25 | 20–30 | 20–30 | 20–30 | 20–30 | 20–30 | 20–30 | 20–30 |
| Marine life | Peak | Busy | Busy | Steady | Busy | Steady | Busy | Busy | Busy | Busy | Peak | Busy |
| Best time | Peak | Peak | Peak | Peak | Peak |
Long-term averages, 2016–2025. Visibility is estimated from satellite chlorophyll-a. Water temperature is the surface mean; it is cooler at depth.
The Cairns diving season
January to April · Off season
4 months- Water temperature
- 28–30 °C
- Visibility
- 20–30 m
- Rain
- 18 days a month
Diving conditionsIt rains more. The sea is calmer.
Marine lifeWhale shark (likely), Tiger shark (hit-or-miss), Reef manta (hit-or-miss) peak at Cairns in these months.
May · Shoulder season
1 month- Water temperature
- 27–27 °C
- Visibility
- 15–25 m
- Rain
- 17 days a month
Diving conditionsRain is frequent topside. The sea is rougher. The wind is up.
Marine lifeTiger shark (hit-or-miss), Reef manta (hit-or-miss) peak at Cairns in these months.
June to November · Peak season
6 months- Water temperature
- 25–28 °C
- Visibility
- 20–30 m
- Rain
- 9 days a month
Diving conditionsExpect some swell. It rains less.
Marine lifeWhale shark (likely), Tiger shark (hit-or-miss), Reef manta (hit-or-miss) peak at Cairns in these months.
December · Shoulder season
1 month- Water temperature
- 29–29 °C
- Visibility
- 20–30 m
- Rain
- 12 days a month
Diving conditionsRain is frequent topside. The wind eases. The sea is calmer.
Marine lifeGreat hammerhead (hit-or-miss), Tiger shark (hit-or-miss) peak at Cairns in these months.
- Spring tides run 2.3 m against 1.0 m on neaps, so currents build around the full and new moon.
- Water temperature is satellite sea-surface temperature, so expect it cooler below the thermocline.
- Visibility is estimated from satellite chlorophyll-a.
Cairns water temperature and weather
2,572 underwater observation records · 32 surveyed years of ocean data · 10 years of sea temperature
Water & weather
Cairns water temperature by month
The dashed line is the monthly average. Eight days in ten fall inside the band.
10th to 90th percentile rangemonthly mean
Seas top 2.5 m on under 1% of days. Enough to cancel a liveaboard crossing
Gusts over 40 km/h, about where a day boat stays in port
4 of them bring heavy rain
| Month | Swell | Gusts over 40 km/h | Wet days | Heavy rain | Air | Daylight |
|---|---|---|---|---|---|---|
| January | 1.2 m | 15% | 20 | 10 | 29 °C | 12.9 h |
| February | 1.5 m | 15% | 18 | 8 | 29 °C | 12.5 h |
| March | 1.5 m | 23% | 19 | 9 | 28 °C | 12.1 h |
| April | 1.7 m | 47% | 17 | 3 | 28 °C | 11.6 h |
| May | 1.7 m | 58% | 17 | 2 | 26 °C | 11.2 h |
| June | 1.7 m | 41% | 13 | 1 | 25 °C | 11.0 h |
| July | 1.7 m | 40% | 12 | 1 | 24 °C | 11.1 h |
| August | 1.6 m | 33% | 10 | 1 | 24 °C | 11.4 h |
| September | 1.6 m | 28% | 7 | 0 | 25 °C | 11.9 h |
| October | 1.4 m | 11% | 4 | 1 | 26 °C | 12.4 h |
| November | 1.1 m | 7% | 6 | 1 | 27 °C | 12.8 h |
| December | 1.6 m | 11% | 12 | 5 | 28 °C | 13.0 h |
Swell is the rough end of the month: nine days in ten come in under it. Sea temperature covers 10 years, waves 4.
Pick your week
48 weeks from the daily record. Darker is better, against this site's own year. Pick a month for the detail.
| Week 1 | January week 1: Poor | February week 1: Poor | March week 1: Poor | April week 1: Moderate | May week 1: Moderate | June week 1: Good | July week 1: Moderate | August week 1: Moderate | September week 1: Moderate | October week 1: Excellent | November week 1: Excellent | December week 1: Good |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Week 2 | January week 2: Poor | February week 2: Poor | March week 2: Poor | April week 2: Poor | May week 2: Moderate | June week 2: Good | July week 2: Good | August week 2: Moderate | September week 2: Moderate | October week 2: Good | November week 2: Excellent | December week 2: Moderate |
| Week 3 | January week 3: Poor | February week 3: Poor | March week 3: Poor | April week 3: Poor | May week 3: Moderate | June week 3: Good | July week 3: Excellent | August week 3: Excellent | September week 3: Good | October week 3: Excellent | November week 3: Excellent | December week 3: Poor |
| Week 4 | January week 4: Poor | February week 4: Poor | March week 4: Poor | April week 4: Poor | May week 4: Good | June week 4: Moderate | July week 4: Good | August week 4: Excellent | September week 4: Excellent | October week 4: Excellent | November week 4: Good | December week 4: Poor |
January, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Poor | 29 °C | 1.1 m | 27 km/h | 59% |
| Week 2 | Poor | 29 °C | 1.2 m | 29 km/h | 62% |
| Week 3 | Poor | 29 °C | 1.3 m | 30 km/h | 64% |
| Week 4 | Poor | 29 °C | 1.2 m | 31 km/h | 69% |
February, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Poor | 29 °C | 1.3 m | 31 km/h | 66% |
| Week 2 | Poor | 30 °C | 1.3 m | 29 km/h | 53% |
| Week 3 | Poor | 30 °C | 1.5 m | 29 km/h | 58% |
| Week 4 | Poor | 29 °C | 1.6 m | 30 km/h | 64% |
March, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Poor | 29 °C | 1.4 m | 29 km/h | 61% |
| Week 2 | Poor | 29 °C | 1.5 m | 30 km/h | 65% |
| Week 3 | Poor | 29 °C | 1.5 m | 33 km/h | 68% |
| Week 4 | Poor | 29 °C | 1.4 m | 34 km/h | 60% |
April, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Moderate | 29 °C | 1.5 m | 35 km/h | 50% |
| Week 2 | Poor | 29 °C | 1.7 m | 40 km/h | 53% |
| Week 3 | Poor | 28 °C | 1.8 m | 40 km/h | 57% |
| Week 4 | Poor | 28 °C | 1.8 m | 40 km/h | 59% |
May, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Moderate | 27 °C | 1.8 m | 40 km/h | 61% |
| Week 2 | Moderate | 27 °C | 1.7 m | 42 km/h | 59% |
| Week 3 | Moderate | 27 °C | 1.7 m | 43 km/h | 56% |
| Week 4 | Good | 26 °C | 1.5 m | 41 km/h | 45% |
June, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Good | 26 °C | 1.5 m | 39 km/h | 39% |
| Week 2 | Good | 26 °C | 1.4 m | 38 km/h | 41% |
| Week 3 | Good | 26 °C | 1.6 m | 38 km/h | 41% |
| Week 4 | Moderate | 25 °C | 1.8 m | 40 km/h | 48% |
July, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Moderate | 25 °C | 1.8 m | 40 km/h | 50% |
| Week 2 | Good | 25 °C | 1.7 m | 39 km/h | 40% |
| Week 3 | Excellent | 25 °C | 1.6 m | 37 km/h | 34% |
| Week 4 | Good | 25 °C | 1.6 m | 38 km/h | 35% |
August, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Moderate | 25 °C | 1.7 m | 38 km/h | 42% |
| Week 2 | Moderate | 25 °C | 1.6 m | 37 km/h | 37% |
| Week 3 | Excellent | 25 °C | 1.5 m | 36 km/h | 23% |
| Week 4 | Excellent | 25 °C | 1.6 m | 36 km/h | 25% |
September, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Moderate | 25 °C | 1.7 m | 36 km/h | 31% |
| Week 2 | Moderate | 25 °C | 1.7 m | 37 km/h | 34% |
| Week 3 | Good | 25 °C | 1.6 m | 36 km/h | 26% |
| Week 4 | Excellent | 26 °C | 1.5 m | 31 km/h | 14% |
October, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Excellent | 26 °C | 1.5 m | 31 km/h | 11% |
| Week 2 | Good | 26 °C | 1.5 m | 31 km/h | 17% |
| Week 3 | Excellent | 27 °C | 1.3 m | 27 km/h | 17% |
| Week 4 | Excellent | 27 °C | 1.1 m | 26 km/h | 11% |
November, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Excellent | 27 °C | 1.2 m | 27 km/h | 11% |
| Week 2 | Excellent | 28 °C | 1.2 m | 28 km/h | 14% |
| Week 3 | Excellent | 28 °C | 1.1 m | 28 km/h | 20% |
| Week 4 | Good | 28 °C | 1.1 m | 27 km/h | 28% |
December, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Good | 29 °C | 1.4 m | 27 km/h | 31% |
| Week 2 | Moderate | 29 °C | 1.6 m | 29 km/h | 35% |
| Week 3 | Poor | 29 °C | 1.5 m | 29 km/h | 40% |
| Week 4 | Poor | 29 °C | 1.3 m | 27 km/h | 50% |
10 years of daily records, averaged into weeks.
Gear & storms
What to wear
Off the coldest water of each month, not the average — that is what the suit has to cope with.
| January | February | March | April | May | June | July | August | September | October | November | December | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Suit | January: skin | February: skin | March: skin | April: skin | May: 3 mm | June: 3 mm | July: 3 mm | August: 3 mm | September: 3 mm | October: 3 mm | November: 3 mm | December: skin |
- Dec–Aprskin or 3 mm shorty
- May–Nov3 mm full suit
Swell through the year
The rough end of each month — nine days in ten come in under it.
Amber is over 2.5 m.
Tides
Tropical storms
7 of the last 30 Marchs saw a tropical storm pass within 250 km. Anything has been recorded Dec–Apr.
Share of the last 30 years with a storm that month.
- NOAASea surface temperature, from OISST and MUR
- ERA5Wind, waves, rain and air temperature, via Open-Meteo
- OBISMarine species records within 60 km
- IBTrACSTropical cyclone tracks, 1996 to 2025
Cairns marine life — what you'll see diving
| Species | When | Observed window | Reliability | Evidence | Records |
|---|---|---|---|---|---|
| Napoleon wrasse | All year | Near-guaranteed | 291 | ||
| Whitetip reef shark | All year | Near-guaranteed | 231 | ||
| Bumphead parrotfish | All year | Near-guaranteed | 95 | ||
| Green turtle | All year | Near-guaranteed | 618 | ||
| Bluespotted ribbontail ray | All year | Near-guaranteed | 195 | ||
| Saltwater crocodile | All year | Likely | 275 | ||
| Hawksbill turtle | All year | Likely | 55 | ||
| Blacktip reef shark | All year | Likely | 88 | ||
| Whale shark | Jan, Nov | Likely | 120 | ||
| Humpback whale | Jul–Aug | Likely | 64 | ||
| Grey reef shark | All year | Likely | 35 | ||
| Ocellated eagle ray | All year | Hit-or-miss | 28 | ||
| Great hammerhead | Dec | Hit-or-miss | 267 | ||
| Ornate wobbegong | May–Jun | Hit-or-miss | 10 | ||
| Loggerhead turtle | Mar | Hit-or-miss | 8 | ||
| Dugong | Mar, May | Hit-or-miss | 9 | ||
| Minke whale | Jul | Hit-or-miss | 8 | ||
| Bigeye trevally | May, Dec | Hit-or-miss | 39 | ||
| Tiger shark | Mar, May, Aug, Dec | Hit-or-miss | 41 | ||
| Spinner dolphin | Apr–May, Jul, Dec | Hit-or-miss | 12 | ||
| Reef manta | Jan, May, Jul | Hit-or-miss | 9 | ||
| Camouflage grouper | Aug, Dec | Hit-or-miss | 8 |
- Observed window
- Months with records. Peak is where most of them fall.
- Reliability
- Near-guaranteed in 60% of surveyed years or more
- Likely 30% to 60%
- Hit-or-miss under 30%
- Evidence
- Years it was seen, out of the years anyone surveyed.
- Records
- OBIS sightings within 60 km.
These are sightings people logged, not a full survey of the reef. A species missing from a month may just mean nobody recorded one.
Diving Cairns — common questions
- When is the best time to dive Cairns?
- The pull is the outer Great Barrier Reef. That does not change through the year, so go when the weather is best: July to November. The full season runs June to November.
- When is the diving season in Cairns?
- The diving season in Cairns runs June to November, and it is at its best July to November.
- Is the diving in Cairns good for beginners?
- Yes. It suits Open Water divers, so it works for a first trip after certification.
- How warm is the water in Cairns?
- Between 25 and 30 °C at the surface across the year, coldest in August and warmest in February. It runs cooler below the thermocline.
- What wetsuit do I need in Cairns?
- A 3 mm full suit covers the coldest water of the year. In the warmest months a skin or 3 mm shorty is enough.
- What is the visibility like in Cairns?
- Roughly 15 to 30 m depending on the month. That is estimated from satellite chlorophyll-a rather than measured in the water.
- What will I see diving Cairns?
- The most consistently recorded species are Napoleon wrasse (near-guaranteed), Whitetip reef shark (near-guaranteed) and Bumphead parrotfish (near-guaranteed), from 2,572 records within 60 km.
- Does Cairns get tropical storms?
- Yes. Over 30 years of records a storm passed within 250 km in Dec–Apr, most often in March at 7 of 30 years.
- Is there current in Cairns?
- The tide rises and falls 2.3 m around the full and new moon, against 1.0 m in between. How much of that becomes current depends on the shape of the channel.
- When should I avoid Cairns?
- February–March are the weakest months for conditions.
- How do you dive Cairns?
- Mostly from liveaboards and day boats. Trips run through the season, Jun–Nov.