Cook Is
Best Time to Dive in the Cook Islands
21.23°S 159.85°W
The best conditions run June to October, when the rain backs off — 10 wet days a month instead of 16. Too few records to show a wildlife season, so the weather picks the month. The wider season runs June to November.
- Best time
- Jun–Oct
- Water
- 25–28 °C
- Visibility
- 30–40 m
- Season runs
- Jun–Nov
- Dived from
- day boat
- Tidal range
- 0.4–0.8 m
- Species logged
- 4
Worth knowing: 88% of days see seas over 1.5 m.
Where it is
444 km across · coastline from Natural Earth 10m
Diving in the Cook Islands — 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 | Moderate | Poor | Poor | Good | Poor | Good | Moderate | Good | Good | Excellent | Good | Poor |
| Water temp (°C) | 27 | 28 | 28 | 28 | 27 | 26 | 25 | 25 | 25 | 25 | 25 | 27 |
| Visibility (m) | 30–40 | 30–40 | 30–40 | 30–40 | 30–40 | 30–40 | 30–40 | 30–40 | 30–40 | 30–40 | 30–40 | 30–40 |
| Marine life | Busy | Steady | Steady | Steady | Steady | Steady | Steady | Steady | Steady | Busy | Steady | Steady |
| Best time | Peak | Peak | Peak | Peak | Peak |
Excellent Good Moderate PoorPeak season Jun–Oct
Long-term averages, 2016–2025. Visibility is estimated from satellite chlorophyll-a. Water temperature is the surface mean; it is cooler at depth.
The Cook Islands diving season
January to April · Shoulder season
4 monthsJFMAMJJASOND
- Water temperature
- 27–28 °C
- Visibility
- 30–40 m
- Rain
- 17 days a month
Diving conditionsIt rains more.
May · Off season
1 monthJFMAMJJASOND
- Water temperature
- 27–27 °C
- Visibility
- 30–40 m
- Rain
- 16 days a month
Diving conditionsIt rains more.
June to November · Peak season
6 monthsJFMAMJJASOND
- Water temperature
- 25–26 °C
- Visibility
- 30–40 m
- Rain
- 10 days a month
Diving conditionsIt rains less.
December · Off season
1 monthJFMAMJJASOND
- Water temperature
- 27–27 °C
- Visibility
- 30–40 m
- Rain
- 17 days a month
Diving conditionsIt rains more.
- Water temperature is satellite sea-surface temperature, so expect it cooler below the thermocline.
- Visibility is estimated from satellite chlorophyll-a.
Cook Islands water temperature and weather
173 underwater observation records · 19 surveyed years of ocean data · 10 years of sea temperature
Water & weather
Cook Islands 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
29
rough days a month
Seas top 1.5 m on 97% of days. Enough to cancel a day boat
5
blowy days a month
Gusts over 40 km/h, about where a day boat stays in port
13
wet days a month
4 of them bring heavy rain
| Month | Swell | Gusts over 40 km/h | Wet days | Heavy rain | Air | Daylight |
|---|---|---|---|---|---|---|
| January | 3.6 m | 13% | 17 | 6 | 27 °C | 13.2 h |
| February | 3.0 m | 10% | 18 | 8 | 27 °C | 12.7 h |
| March | 2.6 m | 6% | 19 | 6 | 27 °C | 12.1 h |
| April | 3.7 m | 14% | 15 | 4 | 27 °C | 11.5 h |
| May | 4.0 m | 27% | 16 | 4 | 26 °C | 11.0 h |
| June | 4.0 m | 21% | 10 | 2 | 25 °C | 10.7 h |
| July | 3.8 m | 20% | 11 | 3 | 24 °C | 10.8 h |
| August | 3.6 m | 18% | 9 | 3 | 24 °C | 11.3 h |
| September | 3.7 m | 19% | 10 | 2 | 24 °C | 11.9 h |
| October | 3.6 m | 20% | 9 | 2 | 24 °C | 12.5 h |
| November | 3.2 m | 14% | 9 | 3 | 25 °C | 13.0 h |
| December | 3.1 m | 13% | 17 | 6 | 26 °C | 13.3 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: Moderate | March week 1: Moderate | April week 1: Good | May week 1: Poor | June week 1: Good | July week 1: Poor | August week 1: Moderate | September week 1: Good | October week 1: Good | November week 1: Moderate | December week 1: Moderate |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Week 2 | January week 2: Poor | 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: Good | October week 2: Good | November week 2: Good | December week 2: Moderate |
| Week 3 | January week 3: Moderate | February week 3: Poor | March week 3: Moderate | April week 3: Moderate | May week 3: Poor | June week 3: Moderate | July week 3: Good | August week 3: Good | September week 3: Good | October week 3: Good | November week 3: Good | December week 3: Moderate |
| Week 4 | January week 4: Poor | February week 4: Poor | March week 4: Moderate | April week 4: Excellent | May week 4: Moderate | June week 4: Moderate | July week 4: Poor | August week 4: Good | September week 4: Good | October week 4: Good | November week 4: Excellent | December week 4: Moderate |
Excellent Good Moderate PoorBest week to go: second of October
January, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Poor | 27 °C | 3.2 m | 29 km/h | 50% |
| Week 2 | Poor | 27 °C | 3.8 m | 30 km/h | 53% |
| Week 3 | Moderate | 27 °C | 3.8 m | 29 km/h | 57% |
| Week 4 | Poor | 28 °C | 3.2 m | 27 km/h | 62% |
February, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Moderate | 28 °C | 3.0 m | 27 km/h | 69% |
| Week 2 | Poor | 28 °C | 3.1 m | 28 km/h | 69% |
| Week 3 | Poor | 28 °C | 3.1 m | 30 km/h | 61% |
| Week 4 | Poor | 28 °C | 2.9 m | 28 km/h | 51% |
March, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Moderate | 28 °C | 2.9 m | 27 km/h | 56% |
| Week 2 | Poor | 28 °C | 3.1 m | 26 km/h | 66% |
| Week 3 | Moderate | 28 °C | 2.6 m | 25 km/h | 63% |
| Week 4 | Moderate | 28 °C | 2.6 m | 25 km/h | 57% |
April, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Good | 28 °C | 2.9 m | 27 km/h | 55% |
| Week 2 | Good | 28 °C | 3.4 m | 29 km/h | 56% |
| Week 3 | Moderate | 28 °C | 3.8 m | 32 km/h | 49% |
| Week 4 | Excellent | 27 °C | 4.0 m | 33 km/h | 42% |
May, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Poor | 27 °C | 4.0 m | 33 km/h | 46% |
| Week 2 | Poor | 27 °C | 4.0 m | 35 km/h | 58% |
| Week 3 | Poor | 27 °C | 3.9 m | 33 km/h | 56% |
| Week 4 | Moderate | 26 °C | 3.8 m | 29 km/h | 41% |
June, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Good | 26 °C | 3.9 m | 29 km/h | 33% |
| Week 2 | Good | 26 °C | 3.8 m | 31 km/h | 34% |
| Week 3 | Moderate | 26 °C | 4.0 m | 34 km/h | 33% |
| Week 4 | Moderate | 25 °C | 4.1 m | 35 km/h | 32% |
July, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Poor | 25 °C | 3.7 m | 34 km/h | 34% |
| Week 2 | Good | 25 °C | 3.7 m | 32 km/h | 31% |
| Week 3 | Good | 25 °C | 3.8 m | 32 km/h | 34% |
| Week 4 | Poor | 25 °C | 4.4 m | 31 km/h | 38% |
August, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Moderate | 25 °C | 4.4 m | 31 km/h | 33% |
| Week 2 | Good | 25 °C | 3.9 m | 31 km/h | 31% |
| Week 3 | Good | 25 °C | 3.6 m | 31 km/h | 31% |
| Week 4 | Good | 25 °C | 3.6 m | 32 km/h | 30% |
September, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Good | 25 °C | 3.7 m | 32 km/h | 29% |
| Week 2 | Good | 25 °C | 3.6 m | 32 km/h | 29% |
| Week 3 | Good | 25 °C | 3.5 m | 31 km/h | 36% |
| Week 4 | Good | 25 °C | 3.7 m | 32 km/h | 33% |
October, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Good | 25 °C | 3.7 m | 33 km/h | 22% |
| Week 2 | Good | 25 °C | 3.1 m | 33 km/h | 23% |
| Week 3 | Good | 25 °C | 3.2 m | 32 km/h | 29% |
| Week 4 | Good | 25 °C | 3.6 m | 35 km/h | 33% |
November, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Moderate | 25 °C | 3.3 m | 35 km/h | 32% |
| Week 2 | Good | 25 °C | 3.2 m | 32 km/h | 29% |
| Week 3 | Good | 25 °C | 3.2 m | 32 km/h | 29% |
| Week 4 | Excellent | 26 °C | 3.0 m | 30 km/h | 35% |
December, week by week
| Week | Conditions | Water | Swell | Wind | Rain chance |
|---|---|---|---|---|---|
| Week 1 | Moderate | 26 °C | 2.9 m | 29 km/h | 47% |
| Week 2 | Moderate | 26 °C | 3.3 m | 30 km/h | 57% |
| Week 3 | Moderate | 27 °C | 3.1 m | 31 km/h | 55% |
| Week 4 | Moderate | 27 °C | 2.7 m | 28 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: 3 mm | February: skin | March: skin | April: 3 mm | May: 3 mm | June: 3 mm | July: 3 mm | August: 3 mm | September: 3 mm | October: 3 mm | November: 3 mm | December: 3 mm |
- Apr–Jan3 mm full suit
- Feb–Marskin or 3 mm shorty
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
4 of the last 30 Februarys saw a tropical storm pass within 250 km. Anything has been recorded Nov–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
Cook Islands marine life — what you'll see diving
Only 173 records have been logged within 60 km. A thin record is not an empty reef.
| Species | When | Observed window | Reliability | Evidence | Records |
|---|---|---|---|---|---|
| Humpback whale | Aug | Likely | 76 | ||
| Green turtle | All year | Likely | 67 | ||
| Ocellated eagle ray | Jan–Feb, Nov | Hit-or-miss | 12 | ||
| Hawksbill turtle | Jan, Oct | Likely | 9 |
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 the Cook Islands — common questions
- When is the best time to dive the Cook Islands?
- The best conditions run June to October, when the rain backs off — 10 wet days a month instead of 16. Too few records to show a wildlife season, so the weather picks the month. The wider season runs June to November.
- When is the diving season at the Cook Islands?
- The diving season at the Cook Islands runs June to November, and it is at its best June to October.
- Is the diving at the Cook Islands good for beginners?
- Yes. It suits Open Water divers, so it works for a first trip after certification.
- How warm is the water at the Cook Islands?
- Between 25 and 28 °C at the surface across the year, coldest in August and warmest in March. It runs cooler below the thermocline.
- What wetsuit do I need at the Cook Islands?
- 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 at the Cook Islands?
- Roughly 30 to 40 m depending on the month. That is estimated from satellite chlorophyll-a rather than measured in the water.
- What will I see diving the Cook Islands?
- The most consistently recorded species are Humpback whale (likely), Green turtle (likely) and Ocellated eagle ray (hit-or-miss), from 173 records within 60 km.
- Does the Cook Islands get tropical storms?
- Yes. Over 30 years of records a storm passed within 250 km in Nov–Mar, most often in February at 4 of 30 years.
- Is there current at the Cook Islands?
- The tide rises and falls 0.8 m around the full and new moon, against 0.4 m in between. How much of that becomes current depends on the shape of the channel.
- When should I avoid the Cook Islands?
- February is the weakest month for conditions.
- How do you dive the Cook Islands?
- Mostly from day boats. Trips run through the season, Jun–Nov.