Kona Water Temperature at a Glance
Kona water temperature stays warm all year. Ten-year monthly averages for Kailua-Kona run from about 76.6 F (24.8 C) in March to about 81.0 F (27.2 C) in September. That is a swing of less than 5 degrees across the whole year.
For most visitors, that means swimwear is enough for daytime swimming and snorkeling in any month. What changes more than the water is how you feel once you climb out: wind, clouds and the time of day all play a part.
Kona Water Temperature by Month
The list below shows average sea surface temperature for Kailua-Kona by month, based on 10 years of data published by seatemperature.info. On any given day the reading can run a little above or below these averages.
- January: 77.4 F (25.2 C)
- February: 76.8 F (24.9 C)
- March: 76.6 F (24.8 C)
- April: 77.2 F (25.1 C)
- May: 78.3 F (25.7 C)
- June: 79.0 F (26.1 C)
- July: 79.9 F (26.6 C)
- August: 80.6 F (27.0 C)
- September: 81.0 F (27.2 C)
- October: 80.8 F (27.1 C)
- November: 79.9 F (26.6 C)
- December: 78.4 F (25.8 C)
Warmest Months: August to October
The water is warmest from August through October, when averages sit between 80.6 F and 81.0 F. If you get cold easily, this is the most comfortable window for a long swim or a full morning of snorkeling.
Coolest Months: February and March
Late winter brings the coolest water of the year, about 76.6 F to 76.8 F on average. That is still warm by most mainland standards. After a long float with little kicking, you may notice a chill, especially on a cloudy or breezy morning.
The cooler months line up with whale season. Early season starts in November, and peak season runs December through March. If you are visiting then, our whale watching Kona trip, Dolphin and Whale Watching Kailua-Kona, is 2.5 hours with check-in time built into the schedule, and there is no swimming. Whales are wild animals, and this is an El Nino year, so we can never promise sightings or timing. For more on planning around the season, read our Big Island whale season guide.
What Changes How the Water Feels
A monthly average is a good starting point. A few things change how the water feels on the day you go:
- Time of day - The water itself changes little from morning to night, but evening air feels cooler on wet skin, so night snorkels feel colder once you are back on the boat.
- Wind and clouds - A breeze on wet skin can make 78 F water feel cooler than it is.
- How long you stay in - A quick swim feels different from a long, slow float.
- How much you move - Kicking and swimming keep you warm. Floating still, like you do on a night snorkel, lets you cool off faster.
What to Wear on Each Dolphin Discoveries Tour
Manta Ray Night Snorkel
Our manta ray night snorkel Kona tour runs 2 hours, with about 30 minutes in the water, for ages 6 to 70. Masks, snorkels, short sleeve wetsuit tops and pool noodles are provided, and snorkel vests are available to rent. Arrive in swim attire with a light cover-up, and bring a towel for after the trip. Guests must know how to swim.
The boat ride from Keauhou Bay to the manta site takes about 5 minutes. The water there is 35 to 40 feet deep, and you float flat at the surface while holding a lit board. Because you stay still for most of the swim, the wetsuit top makes a real difference, even in the warmer months. To learn more about the animals you will see, visit our manta ray learning page.
Daytime Snorkel Tours
Our daytime Kona snorkel tours include the Deluxe Kona Snorkel Adventure (Two Spots), $119.99 for 5 hours total with 4 hours on the water. The Captain Cook snorkel tour is $99.99 for 3.5 hours including check-in time. The Morning Captain Cook Snorkel Adventure is also $99.99 and 3.5 hours including check-in time, with a slower pace for new snorkelers. All three are for ages 6 to 70.
Your snorkel gear is handed out at check-in. Swimwear is enough for most people in any month, and a rash guard helps with sun protection on a long morning in the water.
Dolphin and Whale Watching
There is no swimming on this tour, so dress for the boat instead of the water. Our boats are small-group RHIBs (rigid-hull inflatable boats) with open-air seating. Bring a light layer for breeze and spray. The tour is $99.99 for guests ages 5 to 70.
Planning Tips by Season
- November to March: average water runs from about 76.6 F to 79.9 F. This is the coolest stretch of the year, and it overlaps with whale season.
- April to July: averages climb from about 77.2 F to 79.9 F.
- August to October: the warmest water, about 80.6 F to 81.0 F.
Before any tour, check our Know Before You Go page for check-in details, waivers and what to bring.
Frequently Asked Questions About Kona Water Temperature
What is the Kona water temperature in winter?
From December through February, average water temperature in Kailua-Kona runs from about 76.8 F to 78.4 F. March is the coolest month, at about 76.6 F.
When is the water warmest in Kona?
September is the warmest month, at about 81.0 F on average. August and October are close behind, at 80.6 F and 80.8 F.
Do I need a wetsuit to snorkel in Kona?
Most people are comfortable in swimwear for daytime snorkeling in any month. On our Manta Ray Night Snorkel, short sleeve wetsuit tops are provided for every guest.
Can I snorkel in Kona in December?
Yes. Average water temperature in December is about 78.4 F. December is also part of peak whale season, which runs December through March.
Where do Dolphin Discoveries tours start?
Check in at our shop in the Keauhou Shopping Center, 78-6831 Ali'i Dr Suite F-146, Kailua-Kona. Boats depart from Keauhou Bay.
Plan Your Time in the Water
Kona's ocean is warm enough to enjoy in every month, with a few degrees of difference between late winter and early fall. Pick the season that suits you, pack swimwear and a light layer, and book your tour online. If you have questions, call us at (808) 322-8000.
