What is the Weather Like in Tonga in September?
September is a great time to be in the islands of Tonga. It’s one of the months with the least amount of rain, accompanied by balmy temperatures, all while the busy tourist season starts to quieten down. The whales are still tending to their young in Tonga’s waters, where calves are usually older and more inquisitive, making for amazing whale swimming experiences. Additionally, Vava’u is alive at the beginning of the month with the annual Blue Water Festival. All in all, it’s hard not to love Tonga in September. Learn more about the temperatures, rainfall and more in this guide to the Tonga weather in September.
Before we jump into this weather guide for September, be sure to bookmark Tonga Weather by Month: What is the Weather Like in Tonga? for more advice.
5 Tips for Visiting Tonga in September
- September is usually considered the best month to swim with whales in most island groups – see why in When is the Whale Season in Tonga + Best Months
- The nights feel considerably cooler than the day, so you’ll be glad to pack a light jacket
- September 17th is the prince’s birthday public holiday, so expect shops and services to be closed on this day (or the following Monday if it falls on a Sunday)
- While September is still in the dry season, there are often a few rainy days
- It is still the peak season in September so be sure to make your bookings early to avoid disappointment!
Typical Temperatures in September
One of Tonga’s coolest months, September has a maximum average temperature of 29°C / 78°F and lows of 19°C / 66°F. You’ll still want to pack at least one warmer layer for boat trips and cooler evenings.
The coolest areas are in the southern islands, such as Tongatapu and ‘Eua, while you’ll find a little more heat in the islands of Vava’u and Ha’apai.
Temperatures Across Tonga
- Tongatapu & Nuku’alofa – The average maximum temperature is 25°C / 78°F and the average minimum temperature is 19°C / 66°F
- Vava’u – The average maximum temperature is 27°C / 81°F and the average minimum temperature is 20°C / 68°F
- Ha’apai – The average maximum temperature is 26°C / 79°F and the average minimum temperature is 20°C / 68°F
- ‘Eua – The average maximum temperature is 25°C / 78°F and the average minimum temperature is 19°C / 66°F
- The Niuas – The average maximum temperature is 29°C / 84°F and the average minimum temperature is 23°C / 73°F.
Sea Temperature in September
The average sea temperature in September in Tonga is 24°C / 75°F, some of the coldest sea temperatures of the year. Wet suits are usually worn during snorkelling and whale swimming tours.
Hours of Sun in September
Despite being the “dead of winter” in September, days are still long with around 12 hours of daylight each day. Visitors will also likely experience plenty of sun, with an average of 5 bright sunshine hours each day!
UV Levels During September
September is the winter month in Tonga with the highest UV levels, so wearing sunscreen is essential. The UV level in September is typically 10 UV index around midday. For more sun protection advice, check out The Best Sunscreens for Tonga + Sun Protection Tips.
Sunrise and Sunset During September
September has daylight hours lasting around 12 hours a day in Tonga.
- Sunrise – 6:51 am at the beginning of September and 6:24 am at the end of September
- Sunset – 6:32 pm at the beginning of September and 6:39 pm at the end of September.
Learn more about the local time zone in What is the Tonga Time Zone?
Rainfall in September
Short bursts of rain are what to expect in terms of rainfall in September. With only an average of 13 days of rain in the month, you don’t have to worry about spending too long getting soaked by the skies. Unlike the rest of the year, the southern islands around Tongatapu experience more rain than the northern islands.
Tonga receives an average of 122 mm / 4.8 in of rainfall in the month of September, with around 13 days out of September experiencing rain.
Average Rainfall Across Tonga
- Tongatapu & Nuku’alofa – The average rainfall in September is 122 mm / 4.8 in
- Vava’u – The average rainfall in September is 110 mm / 4.3 in
- Ha’apai – The average rainfall in September is 110 mm / 4.3 in
- ‘Eua – The average rainfall in September is 122 mm / 4.8 in
- The Niuas – The average rainfall in September is 145 mm / 5.7 in.
If you find yourself caught in a rainy spell, no worries! Check out the 15 Things to Do in Tonga on a Rainy Day for ideas.
Tropical Storms in September
Read up more about cyclones in How to Prepare for a Cyclone in Tonga.
Best Places to Visit in Tonga in September
While September is a good month to visit any of the islands in Tonga, here are a few places especially worth checking out during this time of the year…
Vava’u – Aside from swimming with whales, scuba diving among the coral reefs, game fishing and snorkelling, another reason to go to Vava’u in September is for the annual Vava’u Blue Water Festival, otherwise known as Regatta Week. Check out the celebrations, watch boat races in the Port of Refuge and join the party! Find out more about Vava’u in The Complete Guide to Vava’u.
‘Eua – During this cooler time of the year, it’s a great time to go for a hike in the ‘Eua National Park. Tonga’s southern island is the oldest island of the nation, offering a network of trails to explore the lush rainforest, view amazing cliffs and spot the rare koki (red shining parrot). Find out more in The Complete Guide to ‘Eua.
September Packing List for Tonga
As one of the cooler months in Tonga, you’re going to need a little more than your shorts and T-shirt. Here are a few more suggestions for your packing list!
- High-factor (and reef-safe) sunscreen
- Light bamboo, linen or merino layers (we like the sustainable bamboo clothing of Moso Morrow)
- Light pants/skirt (for the cooler evenings and to cover the skin in areas where you need to dress more modestly)
- Light jacket (for the evenings or for on boat trips)
- Rash vest (we like the UV-protecting Sharkskin rashies)
- Sarong (lavalava)
- Closed walking shoes
- Insect repellent.
Get more packing ideas with The Complete Packing List for Tonga.
More About the Tonga Weather
That’s it for our complete guide to the weather and climate in Tonga in September. Check out the following articles for more weather advice:
- Tonga Weather, Seasons & Climate + Tonga Weather by Month
- The Best Time to Visit Tonga
- The Top Events & Festivals in Tonga