Rarotonga & the Cook Islands Weather, Seasons & Climate + Weather by Month

A Guide to the Weather and Climate in Rarotonga and the Cook Islands

What is the weather like in Rarotonga and the Cook Islands? The Cook Islands has a tropical climate with warm and sunny weather all year round, with its fair share of rainy days too. In this complete guide to the weather, climate and seasons in the Cook Islands, discover the yearly climate of the islands, as well as what the weather is like month-by-month.

Before we begin, make sure you dress for the weather by following the advice in What to Wear in Rarotonga & the Cook Islands: Clothes Packing List.

Rarotonga and Cook Islands Seasons

The Cook Islands has a tropical climate with a hot and humid period between December and March and a drier and cooler period between November and April. The seasons are therefore split into the following:

Dry/Winter season: April to November
Wet/Summer season: December to March

Note that the Cook Islands still experiences rain even during the “dry” season.

Rarotonga and the Cook Islands Year-Round Weather: What is the Annual Climate?

Rarotonga & the Cook Islands Weather, Seasons & Climate + Weather by Month

The Temperature in Rarotonga and the Cook Islands

The Cook Islands experiences warm temperatures all year round due to its position just north of the Tropic of Capricorn and south of the Equator. This means that the Southern Group islands experience cooler temperatures than the Northern Group. Also due to the country’s position, temperatures only mildly fluctuate throughout the year with the main temperature differences being between the dry season and the wet season.

Cook Islands Year-Round Temperature: What is the Average Temperature in the Cook Islands?

The average maximum temperature in the Southern Cook Islands is 27°C (81°F), while the minimum average is 21°C (70°F).

The average maximum temperature in the Northern Cook Islands is 31°C (87°F), while the minimum average is 24°C (76°F).

Scroll down for temperature listings for each month in the Cook Islands.

The Sea Temperature in the Cook Islands

The temperature of the sea (the water temperature) in the Cook Islands is comfortable for swimming all year round with an average yearly sea temperature of 26°C (78°F) in the Southern Group and 29°C (84°F) in the Northern Group.

The highest sea temperatures tend to be experienced during the wet season with the average temperature being 27°C (81°F) between January and April.

The lowest sea temperatures only go down to around 25°C (77°F) during the dry season between June and November.

Again, average sea temperatures month-by-month can be seen in our monthly weather guides below.

Rainfall in the Cook Islands

Don’t be fooled by the labels “dry” and “wet” season. Rainfall can occur all year round in Rarotonga and the Cook Islands. The yearly average rainfall amounts to around 2,000 mm (79″) in the Southern Group and between 1,900 to 2,800 mm (75-110″) in the Northern Group.

As the name suggests, the wet season is when maximum precipitation occurs with about 220 to 250 mm (9 to 10″) falling per month between December and March in the Southern Group. That number is 295 to 300 mm (12 to 13″) for the Northern Group.

In the dry season, the Cook Islands still gets a share of rainy spells with an average of 70 to 120 mm (3 to 5″) precipitation per month between May and September. That number is 115 to 150 mm (4.5 to 6″) for the Northern Group.

Due to the Cook Islands’ maritime climate and flat terrain, rainy spells come in quick, heavy and often short bursts over the islands.

Which Islands Receive the Least Rain in the Cook Islands?

The Southern Group receives less rainfall in the Cook Islands than the Northern Group. Rarotonga is the southern island with the most rain, while Mitiaro is the southern island with the least. Aitutaki also has a notably drier climate than Rarotonga.

Daylight and Sunshine Hours in the Cook Islands

The Cook Islands experiences long days all year round with daylight hours spanning 13 hours per day from October to February. In the dry season months, this only drops down to 11 hours with the shortest days being in June.

With the long days comes plenty of sunshine. The most sunshine hours are experienced between October and April, averaging at 6 hours per day. The month with the highest sunshine hours is typically December at around 7.5 hours, while the month with the least is July with around 2.8 hours.

Severe Weather Events

Tropical cyclones that develop in the South Pacific have a risk of affecting the Cook Islands. The cyclone season in the Cook Islands and the South Pacific starts in November and ends in April, i.e. during the wet season. The peak months for cyclone risk are the months of December, January and February. There is also a higher risk of cyclone activity during an El Nino year.

The Cook Islands has a history of cyclone activity. The worst cyclones have been the category 3 Cyclone Martin (1997) with 19 fatalities in the Northern Cook Islands, while 2005 saw three cyclones, Cyclones Percy, Meena and Nancy impact the Cook Islands. Cyclone Pat (2010) was especially damaging to the island of Aitutaki. This is by no means an all-inclusive list, so check out our month-by-month weather guides for October, November, December, January, February and March, which include the history of cyclones in the Cook Islands.

The Cook Islands is well-prepared with emergency procedures should a cyclone occur, which you can learn more about in Cyclone Safety in the Cook Islands: How to Prepare for a Cyclone.

Rarotonga and the Cook Islands Weather by Month

January Weather in the Cook Islands

The year gets off to a hot and humid start in the Cook Islands, as it’s the midst of the wet season. It’s also the cyclone season in the South Pacific, so be aware of cyclone warnings – see our cyclone guide for more details. Otherwise, the country is vibrant with New Year celebrations, particularly on Rarotonga.

Average temperature: 28°C / 82°F in the day, 23°C/74°F at night
Average sea temperature: 27°C / 81°F
Average rainfall: 267 mm / 10.5″
Daylight hours: 13 hours

For more in-depth information, see our complete guide to Rarotonga & the Cook Islands Weather in January.

February Weather in the Cook Islands

It’s still the wet season in the Cook Islands so expect bursts of heavy rain in February. Temperatures are warm and it’s humid but at least the days are long and there are still plenty of sunshine hours for those seeking some sun. February is also considered the low season, which is a cheap and quiet time to experience the islands. See the 10 Reasons to Travel in the Low Season in the Cook Islands for more benefits.

Average temperature: 29°C / 84°F in the day, 23°C / 73°F at night
Average sea temperature: 27°C / 81°F
Average rainfall: 237 mm / 9.3″
Daylight hours: 13 hours

For more in-depth information, see our complete guide to Rarotonga & the Cook Islands Weather in February.

March Weather in the Cook Islands

The wet season continues, with still the slight risk of cyclones developing. The Northern Group experience their highest rainfall and temperatures of the year, while the Southern Group is not close behind.

Average temperature: 29°C / 84°F in the day, 23°C / 74°F at night
Average sea temperature: 28°C/83°F
Average rainfall: 220 mm / 8.7″
Daylight hours: 12 hours

For more in-depth information, see the complete guide to Rarotonga & the Cook Islands Weather in March.

April Weather in the Cook Islands

April is the transitional month from the wet season to the dry season, still bringing some “April showers” along with it. Temperatures and humidity are still quite high, but at least it’s the last month of the cyclone season.

Average temperature: 28°C / 82°F in the day, 22°C / 69°F at night
Average sea temperature: 27°C / 81°F
Average rainfall: 231 mm / 9.1″
Daylight hours: 12 hours

For more in-depth information, see our full guide to Rarotonga & the Cook Islands Weather in April.

May Weather in the Cook Islands

May is the official start to the dry season, where temperatures start to get cooler and the humidity drops. There are fewer rain days but when it does rain, it’s usually heavy showers. The UV levels are also not quite as intense as in summer, averaging around 7 UV index at midday. May is a good time to visit popular islands, like Rarotonga and Aitutaki, before the tourist crowds arrive.

Average temperature: 27°C / 81°F in the day, 21°C / 70°F at night
Average sea temperature: 26°C / 79°F
Average rainfall: 205 mm / 8.1″
Daylight hours: 11 hours

For more in-depth information, see our complete guide to Rarotonga & the Cook Islands Weather in May.

June Weather in the Cook Islands

The dry season really kicks into gear with cooler and much drier days than what’s experienced in summer. Sea temperatures are also dropping but still warm enough for a comfortable swim. Note that the first Monday of June is The Sovereign’s Birthday, a public holiday in the Cook Islands, so expect some businesses to be closed on this day.

Average temperature: 26°C / 79°F in the day, 20°C / 68°F at night
Average sea temperature: 25°C / 77°F
Average rainfall: 120 mm / 4.7″
Daylight hours: 11 hours

For more in-depth information, see the complete guide to Rarotonga & the Cook Islands Weather in June.

July Weather in the Cook Islands

July is a popular time to be in the Cook Islands, with the weather becoming more and more appealing for those wishing to escape the cold winter of their own country. It’s also the time of year when you can spot humpback whales in the Cook Islands. The first Friday of the month is a public holiday, Ra o te Ui Ariki, so some businesses will be closed on this day.

Average temperature: 25°C / 77°F in the day, 19°C / 66°F at night
Average sea temperature: 25°C / 77°F
Average rainfall: 102 mm / 4″
Daylight hours: 11 hours

For more in-depth information, see the complete guide to Rarotonga & the Cook Islands Weather in July.

August Weather in the Cook Islands

August is one of the Cook Islands’ coolest months, which is still hot enough for travellers to enjoy a tropical and sunny getaway. But you’ll be thankful for bringing a light jacket for the cooler evenings or when darting around lagoons by boat. Note that August 4 is Consitution Day in the Cook Islands, a public holiday where some businesses are closed.

Average temperature: 25°C / 77°F in the day, 19°C / 66°F at night
Average sea temperature: 24°C / 75°F
Average rainfall: 152 mm / 6″
Daylight hours: 11 hours

For more in-depth information, see the complete guide to Rarotonga & the Cook Islands Weather in August.

September Weather in the Cook Islands

September is usually an ideal month for travellers in terms of the weather. It’s warm but not too hot, mostly dry with usually 5 days of the month experiencing rain, and it’s still a good time for water clarity when diving, as well as for spotting humpback whales.

Average temperature: 26°C / 79°F in the day, 19°C / 66°F at night
Average sea temperature: 24°C / 75°F
Average rainfall: 132 mm / 5.2″
Daylight hours: 12 hours

For more in-depth information, see the complete guide to Rarotonga & the Cook Islands Weather in September.

October Weather in the Cook Islands

Although October isn’t as popular of a month to visit Rarotonga and the Cook Islands, it’s still idyllic weather for most travellers. Days are long and mostly dry. The sea temperatures rise slightly, making it a good time for snorkelling and diving. We can’t think of a reason not to visit the Cook Islands in October!

Average temperature: 26°C / 79°F in the day, 20°C / 67°F at night
Average sea temperature: 25°C / 77°F
Average rainfall: 121 mm / 4.8″
Daylight hours: 13 hours

For more in-depth information, see the complete guide to Rarotonga & the Cook Islands Weather in October.

November Weather in the Cook Islands

November is the month when you can really feel the transition from the dry season to the wet season in the Cook Islands. Days are getting hotter, it’s starting to get more humid, and the rain gets more frequent towards the end of the month. Nevertheless, it’s the tourist low season so it’s a good time to experience the last of the good weather before the wet season gets into full swing.

Average temperature: 27°C / 81°F in the day, 21°C / 70°F at night
Average sea temperature: 25°C / 77°F
Average rainfall: 174 mm / 6.9″
Daylight hours: 13 hours

For more in-depth information, see the complete guide to Rarotonga & the Cook Islands Weather in November.

December Weather in the Cook Islands

The wet season is well and truly here, where downpours are often heavy but short before the sun comes back out again. It’s also the cyclone season, so it’s best to be aware of the cyclone and weather warnings. There are plenty of public holidays where the country shuts down for Christmas and New Year. Also, be aware that the holiday season is a busy time to travel to and between the Cook Islands, so make your bookings well in advance.

Average temperature: 28°C / 82°F in the day, 22°C / 73°F at night
Average sea temperature: 26°C / 79°F
Average rainfall: 229 mm / 9″
Daylight hours: 13 hours

For more in-depth information, see the complete guide to Rarotonga & the Cook Islands Weather in December.

Frequently Asked Questions About the Weather in Rarotonga and the Cook Islands

Finally, here are some of the most common questions about the weather in Rarotonga and the Cook Islands by travellers across the internet.

Does it Get Cold in the Cook Islands?

No, it does not get cold in the Cook Islands, as the lowest average temperature is 19°C / 66°F only in the dry season (and on Rarotonga and at night). One of the lowest temperatures ever recorded on Rarotonga was 12°C / 54°F.

What is the Coldest Month in Rarotonga?

The coldest months in Rarotonga are both July and August. The average temperature throughout the day is 25°C / 77°F.

Is the Water Warm in Rarotonga?

Yes, the water is relatively warm in Rarotonga at an average temperature of 26°C (78°F).

More About the Weather, Seasons and Climate in Rarotonga and Cook Islands

That’s it for our complete guide to the weather and climate in Rarotonga and the Cook Islands. Check out the following articles for more weather advice:

At last, enjoy a comprehensive guide to planning a trip to the Cook Islands in The Best Cook Islands Travel Guide.

Author

Laura S.

This article was reviewed and published by Laura, editor-in-chief and co-founder of Cook Islands Pocket Guide. Since arriving solo in the South Pacific over 10 years ago with nothing but a backpack and a background in journalism, her mission has been to show the world how easy (and awesome) it is to explore a paradise such as the Cook Islands. She knows the islands inside out and loves sharing tips on how best to experience Raro’s must-dos and hidden gems. Laura is also the editor of several other South Pacific travel guides.

Contact Laura via our contact page