Rarotonga & the Cook Islands Weather in May

Last Updated: 16 June, 2025

What is the Weather Like in Rarotonga and the Cook Islands in May?

Welcome to winter in Rarotonga and the Cook Islands! However, it’s probably not winter as you know it… The Cook Islands’ winter means that it’s just a little less hot and humid but still warm enough to satisfy beach-lovers with temperatures often around 27°C (80°F).

However, it does take a little longer for the Northern Cook Islands to catch up with the winter trend. For travellers, expect a more tranquil atmosphere than the busier tourist seasons that kick into gear next month. So, learn about the typical temperatures, rainfall and more in this guide to the Rarotonga and Cook Islands weather in May.

Before we jump into this weather guide for May, be sure to bookmark Rarotonga & the Cook Islands Weather, Seasons & Climate and The Best Time to Visit the Cook Islands for more advice.

5 Tips for Visiting the Cook Islands in May

May is considered a tourist shoulder season in the Cook Islands, so look out for good deals on flights and accommodation.
Toward the end of May, you’ll need to plan your trip a bit earlier than during the low season. We recommend booking your trip at least two weeks (or more) in advance.
The visibility for scuba diving and snorkelling is better compared to previous months, so pack the snorkel mask or book a dive trip.
Wear high-factor reef-safe sunscreen to protect your skin and the corals.
While May is during the “dry season”, know that it could still rain at any time. Pack a rain jacket if you plan on doing any of those island hikes.

Rarotonga & the Cook Islands Weather in May

Typical Temperatures in May

Locals will say that the Cook Islands “winter” has begun, but to visitors, it will feel far from your typical winter with temperatures reaching average highs of 27°C (81°F). Expect to experience much warmer temperatures in the Northern Cook Islands.

Temperatures are slightly cooler the further south you go, ending with the coolest in Rarotonga and Mangaia. The lowest temperatures experienced in May are around 21°C (70°F), often at night.

Temperatures Across the Cook Islands

Rarotonga – The average maximum temperature is 27°C (81°F) and the minimum average temperature is 21°C (70°F)
Aitutaki – The average maximum temperature is 28°C (82°F) and the minimum average temperature is 22°C (72°F)
Mangaia – The average maximum temperature is 27°C (81°F) and the minimum average temperature is 21°C (70°F)
Mitiaro – The average maximum temperature is 28°C (82°F) and the minimum average temperature is 22°C (72°F)
Manihiki (North) – The average maximum temperature is 31°C (88°F) and the minimum average temperature is 25°C (77°F)
Penrhyn (North) – The average maximum temperature is 31°C (88°F) and the minimum average temperature is 25°C (77°F).

Sea Temperature in May

The Cook Islands has warm sea temperatures all year round, but start to drop a little after the summer season ends and the dry season begins in May. Sea temperatures in May are at an average of 26°C (79°F).

Hours of Sun in May

Typical of a winter season, the days start to get shorter in Rarotonga and the Cook Islands in May. Nevertheless, “short days” in the Cook Islands might not be considered that short with the average daylight hours still being around 11 hours a day.

Sunshine hours are typically around 5 hours a day, which is much more sun than what’s experienced later in the dry season.

UV Levels During May

While UV levels drop significantly compared to the Cook Islands’ summer months, the UV levels are still at 7 UV index around midday. Be sure to wear high-factor sunscreen. For advice on sunscreen, take a look at our The Best Sunscreens for the Cook Islands + Sun Protection Tips.

Sunrise and Sunset During May

May has daylight hours lasting about 11 hours a day in the Cook Islands.

Sunrise: 6:57 am at the beginning of May and 7:09 am at the end of May
Sunset: 6:15 pm at the beginning of May and 6:05 pm at the end of May.

Rainfall in May

While it’s officially the “dry season” that doesn’t mean that the rain has gone for the whole season. Yes, May does still experience some rainy days, typically 9 days out of the month on average. Showers are usually short-lived, however, not causing too much delay to your travel plans or sunbathing sessions.

The Cook Islands receive an average of 205 mm (8.1 in) of rainfall in the month of May, with around 9 days of the month experiencing rain.

Average Rainfall Across the Cook Islands

Rarotonga – The average rainfall in May is 205 mm (8.1 in)
Aitutaki – The average rainfall in May is 174 mm (6.9 in)
Mangaia – The average rainfall in May is 177 mm (7 in)
Mitiaro – The average rainfall in May is 161 mm (6.3 in)
Manihiki (North) – The average rainfall in May is 149 mm (5.9 in)
Penrhyn (North) – The average rainfall in May is 152 mm (6 in).

Tropical Storms in May

The South Pacific cyclone season starts in November and ends in April, so it’s highly unlikely that a tropical cyclone will occur in the Cook Islands in May. Nevertheless, it’s always best to be prepared, as small-scale cyclones have historically developed across the South Pacific in May.

Check out our tips in our guide, Cyclone Safety in the Cook Islands.

For travellers who find cyclones a major concern, perhaps choose a month with less risk, such as July or August.

Best Places to Visit in the Cook Islands in May

May is a good time to visit any of the Cook Islands thanks to the lower tourist numbers, generally better travel deals and idyllic weather. While we list all of the Cook Islands in What are the 15 Islands in the Cook Islands? for inspiration, a few recommendations for May include:

Rarotonga – Rarotonga is the most popular island to visit in the Cook Islands, yet a little quieter in May before the high season really kicks in. Take advantage of its well-developed tourism scene, such as resorts and tours. Showers are often short and sweet in May, so they shouldn’t put too much of a damper on your travel plans. Find out more about what Rarotonga is all about in the 50 Best Things to Do on Rarotonga.

Aitutaki – For similar reasons as visiting Rarotonga, Aitutaki is worth visiting in May not only for its developed tourist scene but for the occasional good deal on flights and accommodation. Aitutaki is a little less rainy than Rarotonga if that’s a determining factor for you. Learn more about what to do in Aitutaki in the 20 Best Things to Do on Aitutaki.

Mangaia – For something a little more off the beaten track, Mangaia is quiet all year round and experiences glorious weather in May. See what Mangaia is all about in the 15 Best Things to Do in Mangaia.

Again, any of the islands are decent to visit during May, so we recommend researching more on the subject using A Guide to the Best Islands of the Cook Islands.

May Packing List for Rarotonga and the Cook Islands

Be prepared for the Cook Islands in May by packing these few seasonal essentials:

Light clothing layers (preferably linen, bamboo or merino so it is super light – we like the sustainable bamboo clothing of Moso Morrow)
Light long-sleeved tops (to cover from the sun and take the edge off those slightly cooler nights)
Light pants/trousers (to cover the knees when appropriate – church service or to protect from mosquitoes when hiking, for example)
Sunhat
Sunglasses
Swimwear
Rash vest (we like the UV-protecting Sharkskin rashies)
Closed walking shoes
Flip-flops/jandals/sandals
Sarong (pāreu – available in the Cook Islands; it’s a good way to cover up when exploring the towns after swimming)
Insect repellent
High-factor sunscreen (that’s reef-safe and water-resistant)
Light rain jacket (just in case).

Get more ideas on what to pack with our guide, What to Pack for Rarotonga & the Cook Islands: Cook Islands Packing List.

More About the Weather in Rarotonga and Cook Islands in May

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

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

Sources:

The information in this guide has been compiled from our extensive research, travel and experiences across the Cook Islands and the South Pacific, accumulated over more than a decade of numerous visits to each destination. Additional sources for this guide include the following:

Cook Islands Tourism Corporation (General travel advice - Updated [2025])
Cook Islands Tourism Industry Council (Tourism trade association - Updated [2025])
Ministry of Foreign Affairs and Immigration (Visa and immigration advice - Updated [2025])
Ministry of Finance & Economic Management (Border restrictions advice - Updated [2025])
Ministry of Agriculture (Biosecurity advice - Updated [2025])
Cook Islands Meteorological Service (Weather forecast and warnings - Updated [2025])
Cook Islands Statistics Office (Statistics and travel data - Updated [2025])
Ministry of Transport (Transport operators and licenses - Updated [2025])
SPTO (Pacific tourism advice - Updated [2025])
Safe Travel (New Zealand travel advisory for the Cook Islands - Updated [2025])
Smart Traveller (Australia travel advisory for the Cook Islands - Updated [2025])

At Cook Islands Pocket Guide, we uphold strict editorial standards to ensure accurate and quality content.

About the Author

Robin C.

This article was reviewed and published by Robin, the co-founder of Cook Islands Pocket Guide. He has lived, worked and travelled across 16 different countries before settling in the South Pacific, so he knows a thing or two about planning the perfect trip in this corner of the world. Robin works and consults regularly with Cook Islands Tourism Corporation, a local government body representing the tourism industry. Robin is also the co-founder of several other South Pacific travel guides and is a regular host of webinars with the South Pacific Tourism Organisation.

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