Australia
Best Time to Dive in Byron Bay / Julian Rocks
28.61°S 153.62°E
What draws people is Julian Rocks — grey nurse sharks, turtles and leopard sharks. Nothing about it runs to a calendar, so it comes down to the weather: go June to September.
- Best time
- Jun–Sep
- Water
- 20–27 °C
- Visibility
- 10–25 m
- Dived from
- day boat
- Tidal range
- 1.0–1.7 m
- Species logged
- 16
Worth knowing: 48% of days see seas over 1.5 m.
Where it is
111 km across · coastline from Natural Earth 10m
Diving in Byron Bay / Julian Rocks — 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 | Good | Moderate | Poor | Moderate | Poor | Excellent | Good | Excellent | Good | Poor | Excellent | Good |
| Water temp (°C) | 26 | 27 | 26 | 25 | 23 | 22 | 21 | 20 | 21 | 22 | 23 | 25 |
| Visibility (m) | 10–20 | 15–25 | 15–25 | 10–20 | 10–20 | 10–20 | 10–20 | 10–20 | 10–20 | 10–20 | 10–20 | 10–20 |
| Marine life | Peak | Peak | Busy | Busy | Busy | Peak | Peak | Peak | Busy | Busy | Peak | Busy |
| Best time | Peak | Peak | Peak | Peak |
Excellent Good Moderate PoorPeak season Jun–Sep
Long-term averages, 2016–2025. Visibility is estimated from satellite chlorophyll-a. Water temperature is the surface mean; it is cooler at depth.
The Byron Bay / Julian Rocks diving season
February to March · Off season
2 monthsJFMAMJJASOND
- Water temperature
- 26–27 °C
- Visibility
- 15–25 m
- Rain
- 19 days a month
Diving conditionsThe wind is up. It rains more.
Marine lifeReef manta (likely), Tiger shark (hit-or-miss) peak at Byron Bay / Julian Rocks in these months.
April · Shoulder season
1 monthJFMAMJJASOND
- Water temperature
- 25–25 °C
- Visibility
- 10–20 m
- Rain
- 15 days a month
Diving conditionsThe wind eases. It rains more.
Marine lifeSardine (hit-or-miss) peaks at Byron Bay / Julian Rocks in these months.
May · Off season
1 monthJFMAMJJASOND
- Water temperature
- 23–23 °C
- Visibility
- 10–20 m
- Rain
- 12 days a month
Diving conditionsRain is frequent topside. The wind eases.
June to January · Peak season
8 monthsJFMAMJJASOND
- Water temperature
- 20–26 °C
- Visibility
- 10–20 m
- Rain
- 11 days a month
Diving conditionsIt rains less.
Marine lifeReef manta (likely), Great white shark (hit-or-miss), Sand tiger shark (likely), Sardine (hit-or-miss) peak at Byron Bay / Julian Rocks in these months.
- Spring tides run 1.7 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.
Byron Bay / Julian Rocks water temperature and weather
6,158 underwater observation records · 32 surveyed years of ocean data · 10 years of sea temperature
Water & weather
Byron Bay / Julian Rocks 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
16
rough days a month
Seas top 1.5 m on 53% of days. Enough to cancel a day boat
0
blowy days a month
Gusts over 40 km/h, about where a day boat stays in port
13
wet days a month
3 of them bring heavy rain
| Month | Swell | Gusts over 40 km/h | Wet days | Heavy rain | Air | Daylight |
|---|---|---|---|---|---|---|
| January | 2.2 m | 0% | 16 | 4 | 27 °C | 13.6 h |
| February | 2.7 m | 1% | 17 | 5 | 27 °C | 13.0 h |
| March | 2.8 m | 1% | 20 | 7 | 26 °C | 12.2 h |
| April | 2.6 m | 0% | 15 | 3 | 24 °C | 11.3 h |
| May | 2.7 m | 0% | 12 | 3 | 22 °C | 10.6 h |
| June | 2.2 m | 0% | 9 | 2 | 20 °C | 10.2 h |
| July | 2.4 m | 0% | 7 | 2 | 20 °C | 10.3 h |
| August | 2.4 m | 0% | 8 | 1 | 21 °C | 11.0 h |
| September | 2.5 m | 0% | 8 | 1 | 23 °C | 11.8 h |
| October | 2.4 m | 0% | 13 | 3 | 24 °C | 12.7 h |
| November | 1.8 m | 0% | 13 | 3 | 26 °C | 13.5 h |
| December | 2.3 m | 0% | 15 | 3 | 27 °C | 13.8 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: Moderate | February week 1: Poor | March week 1: Poor | April week 1: Moderate | May week 1: Poor | June week 1: Excellent | July week 1: Moderate | August week 1: Good | September week 1: Excellent | October week 1: Moderate | November week 1: Good | December week 1: Excellent |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Week 2 | January week 2: Moderate | February week 2: Poor | March week 2: Poor | April week 2: Good | May week 2: Poor | June week 2: Good | July week 2: Good | August week 2: Good | September week 2: Excellent | October week 2: Moderate | November week 2: Excellent | December week 2: Excellent |
| Week 3 | January week 3: Good | February week 3: Moderate | March week 3: Poor | April week 3: Good | May week 3: Poor | June week 3: Good | July week 3: Excellent | August week 3: Excellent | September week 3: Excellent | October week 3: Poor | November week 3: Excellent | December week 3: Good |
| Week 4 | January week 4: Good | February week 4: Poor | March week 4: Poor | April week 4: Poor | May week 4: Moderate | June week 4: Good | July week 4: Good | August week 4: Excellent | September week 4: Moderate | October week 4: Poor | November week 4: Good | December week 4: Moderate |
Excellent Good Moderate PoorBest week to go: second of September
January, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Moderate | 26 °C | 2.3 m | 19 km/h | 53% |
| Week 2 | Moderate | 26 °C | 2.2 m | 19 km/h | 51% |
| Week 3 | Good | 26 °C | 2.2 m | 18 km/h | 46% |
| Week 4 | Good | 26 °C | 2.0 m | 18 km/h | 52% |
February, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Poor | 26 °C | 2.5 m | 19 km/h | 59% |
| Week 2 | Poor | 27 °C | 2.7 m | 19 km/h | 56% |
| Week 3 | Moderate | 27 °C | 2.6 m | 19 km/h | 56% |
| Week 4 | Poor | 27 °C | 2.8 m | 18 km/h | 61% |
March, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Poor | 26 °C | 3.7 m | 18 km/h | 67% |
| Week 2 | Poor | 26 °C | 3.0 m | 18 km/h | 66% |
| Week 3 | Poor | 26 °C | 2.4 m | 17 km/h | 64% |
| Week 4 | Poor | 26 °C | 2.6 m | 17 km/h | 62% |
April, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Moderate | 26 °C | 2.7 m | 17 km/h | 54% |
| Week 2 | Good | 25 °C | 2.7 m | 18 km/h | 44% |
| Week 3 | Good | 25 °C | 2.6 m | 18 km/h | 47% |
| Week 4 | Poor | 25 °C | 2.5 m | 18 km/h | 56% |
May, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Poor | 24 °C | 2.6 m | 17 km/h | 53% |
| Week 2 | Poor | 24 °C | 2.8 m | 17 km/h | 51% |
| Week 3 | Poor | 23 °C | 2.7 m | 17 km/h | 41% |
| Week 4 | Moderate | 23 °C | 2.4 m | 17 km/h | 24% |
June, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Excellent | 22 °C | 2.1 m | 18 km/h | 23% |
| Week 2 | Good | 22 °C | 2.3 m | 18 km/h | 27% |
| Week 3 | Good | 22 °C | 2.1 m | 18 km/h | 27% |
| Week 4 | Good | 21 °C | 2.1 m | 18 km/h | 33% |
July, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Moderate | 21 °C | 2.2 m | 17 km/h | 40% |
| Week 2 | Good | 21 °C | 2.3 m | 17 km/h | 27% |
| Week 3 | Excellent | 21 °C | 2.3 m | 17 km/h | 17% |
| Week 4 | Good | 21 °C | 2.9 m | 17 km/h | 16% |
August, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Good | 21 °C | 2.7 m | 17 km/h | 21% |
| Week 2 | Good | 20 °C | 2.5 m | 18 km/h | 27% |
| Week 3 | Excellent | 20 °C | 2.3 m | 18 km/h | 22% |
| Week 4 | Excellent | 20 °C | 2.3 m | 18 km/h | 22% |
September, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Excellent | 21 °C | 2.1 m | 19 km/h | 24% |
| Week 2 | Excellent | 21 °C | 2.1 m | 20 km/h | 22% |
| Week 3 | Excellent | 21 °C | 2.4 m | 20 km/h | 24% |
| Week 4 | Moderate | 21 °C | 2.6 m | 21 km/h | 30% |
October, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Moderate | 21 °C | 2.4 m | 20 km/h | 34% |
| Week 2 | Moderate | 22 °C | 2.3 m | 20 km/h | 42% |
| Week 3 | Poor | 22 °C | 2.5 m | 21 km/h | 44% |
| Week 4 | Poor | 22 °C | 2.6 m | 21 km/h | 42% |
November, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Good | 23 °C | 2.2 m | 20 km/h | 42% |
| Week 2 | Excellent | 23 °C | 1.9 m | 19 km/h | 40% |
| Week 3 | Excellent | 23 °C | 1.9 m | 19 km/h | 41% |
| Week 4 | Good | 24 °C | 1.9 m | 20 km/h | 47% |
December, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Excellent | 24 °C | 1.8 m | 20 km/h | 51% |
| Week 2 | Excellent | 24 °C | 2.0 m | 20 km/h | 46% |
| Week 3 | Good | 25 °C | 2.3 m | 20 km/h | 43% |
| Week 4 | Moderate | 25 °C | 2.4 m | 19 km/h | 48% |
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: 3 mm | February: 3 mm | March: 3 mm | April: 3 mm | May: 5 mm | June: 5 mm | July: 5 mm + | August: 5 mm + | September: 5 mm + | October: 5 mm | November: 5 mm | December: 5 mm |
- Jan–Apr3 mm full suit
- May–Jun5 mm full suit
- Jul–Sep5 mm with hood and gloves
- Oct–Dec5 mm full suit
Swell through the year
The rough end of each month — nine days in ten come in under it.
Amber is over 1.5 m.
Tides
Tropical storms
1 of the last 30 Februarys saw a tropical storm pass within 250 km. Anything has been recorded Feb–Mar.
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
Byron Bay / Julian Rocks marine life — what you'll see diving
| Species | When | Observed window | Reliability | Evidence | Records |
|---|---|---|---|---|---|
| Humpback whale | Jun–Jul, Sep | Near-guaranteed | 4668 | ||
| Green turtle | All year | Near-guaranteed | 368 | ||
| Zebra shark | Feb–Apr | Likely | 164 | ||
| Ocellated eagle ray | All year | Likely | 67 | ||
| Loggerhead turtle | All year | Likely | 42 | ||
| Ornate wobbegong | All year | Likely | 36 | ||
| Hawksbill turtle | All year | Likely | 56 | ||
| Bottlenose dolphin | All year | Likely | 35 | ||
| Reef manta | Jan–Feb | Likely | 55 | ||
| Bull shark | Dec–Feb, Apr | Hit-or-miss | 53 | ||
| Great white shark | Jul–Aug, Oct | Hit-or-miss | 342 | ||
| Bigeye trevally | Feb–Mar | Hit-or-miss | 38 | ||
| Common dolphin | Jul, Sep | Hit-or-miss | 8 | ||
| Sand tiger shark | Jun–Aug, Nov | Likely | 62 | ||
| Sardine | Apr, Aug–Sep | Hit-or-miss | 47 | ||
| Tiger shark | Dec–Feb, Jun–Jul | Hit-or-miss | 14 |
Peak Present
- 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 Byron Bay / Julian Rocks — common questions
- When is the best time to dive Byron Bay / Julian Rocks?
- What draws people is Julian Rocks — grey nurse sharks, turtles and leopard sharks. Nothing about it runs to a calendar, so it comes down to the weather: go June to September.
- When is the diving season in Byron Bay / Julian Rocks?
- The diving season in Byron Bay / Julian Rocks runs June to September.
- Is the diving in Byron Bay / Julian Rocks good for beginners?
- Yes. It suits Open Water divers, so it works for a first trip after certification.
- How warm is the water in Byron Bay / Julian Rocks?
- Between 20 and 27 °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 Byron Bay / Julian Rocks?
- A 5 mm with hood and gloves covers the coldest water of the year. In the warmest months a 3 mm full suit is enough.
- What is the visibility like in Byron Bay / Julian Rocks?
- Roughly 10 to 25 m depending on the month. That is estimated from satellite chlorophyll-a rather than measured in the water.
- What will I see diving Byron Bay / Julian Rocks?
- The most consistently recorded species are Humpback whale (near-guaranteed), Green turtle (near-guaranteed) and Zebra shark (likely), from 6,158 records within 60 km.
- Does Byron Bay / Julian Rocks get tropical storms?
- Yes. Over 30 years of records a storm passed within 250 km in Feb–Mar, most often in February at 1 of 30 years.
- Is there current in Byron Bay / Julian Rocks?
- The tide rises and falls 1.7 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 Byron Bay / Julian Rocks?
- March, May are the weakest months for conditions.
- How do you dive Byron Bay / Julian Rocks?
- Mostly from day boats. Trips run through the season, Jun–Sep.