On a December morning, just after sunrise, Ko Olina’s four lagoons sit still and glassy, while a handful of people stroll the paved path and salt and plumeria scents float in from the resort gardens. By evening, strings of lights wrap the palms, and a Santa hat shows up on a paddleboard now and then. Ko Olina, on Oahu’s dry leeward coast, makes December a month of warm days, whale-watching and easy beach time.
What is the weather like in Ko Olina in December?
Ko Olina in December is warm and mostly sunny, a little cooler than in the fall, with a brief shower now and then. The leeward corner of Oahu is the island’s driest resort coast, so rain here is rarely the story it can be on the windward side.
| Month | Average high (°F) | Average low (°F) | Rain days | Sea (°F) |
|---|---|---|---|---|
| November | 84.1 | 69.4 | 2.5 | 79.5 |
| December | 82.1 | 66.9 | 2.8 | 78.4 |
| January | 80.9 | 64.7 | 2.8 | 77.6 |
A soft, fresh beginning to the day makes it nice to sit on a lanai with coffee, wearing a T-shirt. By midday the sun is strong enough for the beach, yet the trade winds keep it from feeling heavy. Afternoons are the best stretch for lying by the lagoon, and the light turns gold well before dinner, since daylight lasts a little under eleven hours.
When rain comes, it is usually a short passing shower that darkens the Waianae mountains behind the resort and leaves a rainbow over the lots. Over the month only a few days bring measurable rain, and a soaking all-day downpour is the exception. Showers are more likely on the mountain slopes than at the water.
In December, if a breeze comes off the ocean, the evening may cool down enough that a light layer feels nice at a table outside. Shorts and sundresses work all day. Bring a thin sweater or a light jacket for after dark, and sunscreen, because the December sun here is still strong.
Can you swim in Ko Olina in December?
The water is still warm enough for a nice, long swim, but it has cooled a bit since fall, so give yourself a few minutes to get used to it.
Ko Olina draws families in thanks to four handmade lagoons. Each lagoon is wrapped by rock breakwaters, and that keeps the water within typically far calmer than the open ocean beyond, which suits small children and nervous swimmers well. That is how they usually are, not a promise, so watch the signs and the lifeguards, and follow any flags at the beach.
December brings the year’s largest waves to Oahu’s north and west shores, and out past the breakwaters, this west-facing coast can catch a touch of that same swell. Stay inside the lagoons when the ocean looks rough, and leave the open-water swimming and surf to experienced people.
Snorkelers can look at the fish near the rocks along the lagoon edges. Bring a rash guard if you chill easily, a mask and snorkel, and a towel for the breezy walk back.
What to do in Ko Olina in December
December on this coast is shaped by two things: the holiday spirit and the humpback whales. Resorts put up trees and lights, some hold tree-lighting evenings and carol nights, and Hawaii adds its own touches, like Santa arriving by outrigger canoe and the greeting Mele Kalikimaka. Mornings are often busy with families, so the lagoon paths are best early or late.
Whale watching off the leeward coast
Humpback whales typically appear in Hawaii between November and April, and sightings peak from January through March. In December, early arrivals are already here, so you may spot spouts or a breaching whale from the shoreline or on a boat trip. Whale-watching and snorkel cruises leave from the small harbor next to the resort area, and the morning calm often gives the best viewing conditions.
Binoculars help a lot from the beach or a balcony, and a polarized pair of sunglasses cuts the glare on the water. Whales need a buffer of at least 100 yards from any boat or swimmer. It is a chance, not a promise, and early December may offer fewer sightings than the heart of winter. This outing suits nearly everyone, including older children, who tend to stay interested for the whole trip.
Lagoon days and the shoreline path
A paved walkway links the four lagoons, with small beaches, lawns and rocky edges you can stroll in an hour or so. Along the way you find paddleboards, kayaks and a shallow tide-pool corner where kids can look for small crabs and fish. The soft December light makes this a pleasant walk before breakfast or just before sunset.
Pick a lagoon by mood. Some are busier with families and rentals, others are quieter, with more room to spread out. A picnic on the grass with a view of the water, plus snacks and cold drinks, makes an easy lunch.
Evenings: luau, lights and sunsets
This stretch of coast faces west, so sunsets over the Pacific are a daily event, and in winter the sun often drops into the sea at a lower angle that turns the clouds orange and pink. Many visitors bring a drink and sit on the sand or at a lagoon edge as the light goes. For dinner, a luau is a classic choice here, featuring kalua pork, poke, lomi salmon, haupia and hula, and it works well for families and first-time visitors.
For a quieter evening, restaurants near the marina serve fresh fish, shave ice and plate lunches, and some sit right by the water. In December, the seasonal lights and the cool breeze make outdoor tables especially pleasant.
Golf is a popular daytime option on the coast, since the mild temperatures are kinder than summer. Spa visits, paddleboarding and a short drive to the wider leeward beaches fill out the rest. If the North Shore swell is up, some visitors make the drive across the island to watch the surfers from the sand, standing well back from the water.
A two-day itinerary for Ko Olina in December
Day 1 starts at first light with a stroll beside the lagoon path, while the breeze feels cool and the surface stays glassy. Have breakfast at a café or resort restaurant, then take the morning for a swim and snorkel in the lagoon while the sun is still gentle. Midday is for lunch in the shade, either a plate lunch or a salad by the marina.
In the afternoon, join a whale-watching or snorkel cruise from the harbor, or spend the time on a paddleboard or kayak inside the lagoons. Be back on land for the sunset, which comes early in December, so plan dinner around it. An evening works well with a luau or a table beside the water. If it rains, a spa treatment or a hula or lei-making class at the resort fills the hours.
Day 2 can start slower, with breakfast on the lanai and a lazy morning at a different lagoon from the day before. Rent a beach cabana or bring your own umbrella, since the midday sun is strong even in winter. Lunch can be a picnic or a casual grill.
In the afternoon, play a round of golf, or drive out along the leeward coast to find a quieter beach and watch for whales from the shore. Come back for a late shave ice and a stroll under the holiday lights.
For dinner, choose fresh fish at a restaurant near the marina. On a wet day, shopping, a movie or a visit to a nearby mall or museum keeps things easy, and showers usually pass quickly.
Is Ko Olina busy in December?
Yes, December is one of the busier months at Ko Olina, especially around the Christmas and New Year weeks, when families and mainland visitors fill the resorts.
Early December is calmer, before the school breaks begin, and rooms and rental cars are easier to find. The weeks around the holidays bring peak-season rates, full lagoons and busy restaurants, with luaus and popular dinner spots often booked up.
Book rooms and cars early for those holiday weeks, and make dinner and activity reservations as soon as you know your dates. For the quieter first half of the month, booking a bit later is a more relaxed habit.
Beaches and lagoons are most crowded in the late morning and early afternoon, so go early or late for more space. Highway traffic back toward Honolulu can also be heavy at the start and end of holiday weekends. Reservations for popular island sights such as Diamond Head, Hanauma Bay or the USS Arizona Memorial can fill quickly in this season, so check the official rules before you plan a day there.
What to pack for Ko Olina in December
Bring layers for toasty afternoons and chillier nights, plus some gear for the ocean and those whales.
- For windy nights near the ocean, bring a thin sweater or jacket.
- Swimsuits and a rash guard, for lagoon time and cooler water.
- Pack mineral sunscreen along with a hat, since that sun remains intense.
- Binoculars, for spotting whales from shore or a boat.
- A light rain jacket, for short passing showers.
- Sandals and water shoes, for rocky lagoon edges.
Good to know before you go
December falls just after the Central Pacific hurricane season, which runs from June 1 to November 30. Holiday weeks are busy, so book rooms, cars and dinners early. Lodging at the resorts carries state and county taxes.
| Fee | Amount | Who pays |
|---|---|---|
| State transient accommodations tax | 11% | Guests staying at resorts |
| Oahu county accommodations tax | 3% | Guests staying at resorts |
Ko Olina in December vs November and January
Moving the trip earlier to November gives you slightly warmer air and water, and the whale season is just beginning, so sightings are less common. Crowds are lighter before the holidays, and rooms are easier to find. Rain is similar, with brief showers.
Moving later to January means cooler mornings and evenings, a slightly cooler sea and the peak of whale season. Holiday crowds thin after the New Year, and big winter surf is more likely on the north and west shores. The leeward coast stays among the driest places on the island.
Choose November for warmer swimming and fewer people. Choose December for the festive mood and a good chance at early whales. Choose January for the best whale-watching and a calmer pace once the holidays pass.
Is December a good time to visit Ko Olina?
Absolutely, particularly for couples, families, and anybody seeking holiday lights and warm weather minus the deep chill. The lagoons, sunsets and dry leeward weather make it easy to relax.
It is less ideal for travelers who want empty beaches during the Christmas weeks, or who want guaranteed warm water on every dip. If big surf and crowds bother you, early December is a gentler choice.
On arrival, settle in with a lagoon walk, pick your whale cruise and book a luau or a dinner by the water. What makes December in Ko Olina distinctive is the mix of palm trees strung with lights, a calm lagoon at dawn and a whale spout on the horizon.
Sources
- NOAA NCEI, monthly normals 1991-2020, station USW00022551, checked September 8, 2026
- Open-Meteo Marine API, average 2015-2024, checked September 8, 2026
- sunrise-sunset.org, sunrise and sunset calculated for the 15th of the month, checked September 8, 2026
- NOAA NCEI, normals 1991-2020, stations USW00022551 (Kalaeloa) and USC00519397 (Waikiki), via PLAN-HAWAII.md §1, checked September 24, 2026
- NOAA, Hawaiian Islands Humpback Whale National Marine Sanctuary, Responsible Recreation, checked September 25, 2026
- Hawaii Department of Taxation, Announcement 2025-03 ; City and County of Honolulu, OTAT FAQ, checked September 25, 2026
- NWS Honolulu / Central Pacific Hurricane Center, « 2026 Central Pacific Hurricane Season Outlook », weather.gov/hfo/hurricaneOutlook2026, checked September 24, 2026