The short answer is a resounding yes, but swimming in Hawaii during the month of December is a vastly different experience than it is during the calm, glassy days of summer. As the winter season descends upon the United States, the islands of the central Pacific Ocean remain one of the few places where the water remains invitingly warm. However, the arrival of December brings significant changes to the ocean’s rhythm, dictated by powerful swells and shifting trade winds. For travelers planning a winter getaway, understanding the nuances of the local waters is essential for both enjoyment and safety.
Understanding the Ocean Environment in Winter
While much of the mainland is shivering under layers of snow and ice, the tropical climate of the islands ensures that the water temperature remains remarkably stable. However, the “winter” season in this part of the world is defined more by the movement of water than by the temperature of the air.
Water Temperatures and Thermal Comfort
One of the most frequent questions from visitors is whether the water will be too cold for a comfortable swim. In December, the ocean temperature around the islands typically hovers between 74°F and 77°F (23°C to 25°C). While this is slightly cooler than the peak summer temperatures of 80°F, it remains significantly warmer than the coastal waters of California or the Atlantic Ocean during the same period.
Most swimmers find these temperatures perfectly comfortable for extended periods in the water. For those who are particularly sensitive to the cold or planning long snorkeling sessions, a thin neoprene rash guard or a 2mm shorty wetsuit can provide extra insulation. The air temperature in December is equally pleasant, usually ranging from the low 70s to the low 80s, though the presence of the “Kona winds” or occasional passing rain showers can add a slight chill when you first exit the water.
The Impact of Winter Swells: North vs. South Shores
The most critical factor to consider when swimming in December is the direction of the swell. During the winter months, massive low-pressure systems in the North Pacific generate powerful swells that travel thousands of miles before hitting the northern and western shores of the islands. This is the season of legendary big-wave surfing, where places like the North Shore of Oahu see waves that can reach heights of 30 to 50 feet.
Consequently, swimming on the north-facing beaches of any island in December is often dangerous and, in many cases, impossible. Beaches that were calm and swimmable in July, such as Waimea Bay, become the domain of professional surfers and extreme athletes. Conversely, the southern shores of the islands remain shielded from these northern swells. While the summer months bring south swells to these areas, December is typically characterized by much calmer conditions on the southern and some eastern coasts, making them the primary destination for swimmers and families.
Safe and Serene: Where to Swim in December
Choosing the right beach in December requires a bit of local knowledge. Because the swells can change rapidly, it is always recommended to check daily surf reports and speak with lifeguards before entering the water.
O’ahu: From Waikiki to Ko Olina
On the island of Oahu, Honolulu serves as the hub for winter aquatic activities. Waikiki Beach remains the most popular spot for a reason; its southern orientation keeps the water relatively calm even when the north side of the island is experiencing massive surf. The reef breaks further out help dissipate wave energy, leaving the nearshore waters gentle enough for casual swimming and beginner surf lessons.
For those seeking even more tranquility, the man-made lagoons at Ko Olina Resort on the leeward coast offer year-round protection. These four lagoons are designed to allow seawater to circulate while keeping the heavy surf out, providing a safe environment for children and unconfident swimmers. Another excellent winter option is Hanauma Bay. While it can occasionally be affected by eastern trade winds, its sunken volcanic crater shape provides a natural barrier that keeps the inner reef area calm enough for snorkeling most days in December.
Maui: West and South Shore Sanctuaries
On Maui, the winter swimming scene shifts toward the western and southern coastlines. Kaanapali Beach and Kapalua Bay are iconic destinations, though they are more exposed to northern swells than the southern reaches. If the swell is particularly high, Napili Bay may experience significant surge, so it is vital to monitor the conditions.
The south shore, particularly around Wailea and Makena, offers some of the most consistent swimming conditions in December. Beaches like Ulua Beach are famous for their morning calm, perfect for a pre-breakfast dip or a snorkeling excursion.
Kaua’i and the Big Island Nuances
The “Garden Isle” of Kauai can be challenging in the winter. The North Shore is largely off-limits for swimming during December due to the extreme power of the ocean. Instead, visitors should head to the south shore, where Poipu Beach provides a protected cove that is generally safe for swimming year-round.
On the Big Island, the geography works in favor of the swimmer. The massive mountains of Mauna Kea and Mauna Loa block the trade winds, leaving the Kona Coast remarkably calm. Swimming at Kahaluu Beach Park or snorkeling in the pristine waters of Kealakekua Bay is usually fantastic in December. On the opposite side, near Hilo, the weather is significantly wetter, and the ocean can be more turbulent, though protected spots like Richardson Ocean Park still offer opportunities for a swim.
Marine Life and Snorkeling During the Winter Months
Swimming in December isn’t just about the water—it’s about the incredible life that calls the ocean home during this season. The winter months mark the arrival of some of the islands’ most famous seasonal visitors.
Whale Watching from the Water
December is the beginning of the peak humpback whale season. These majestic creatures migrate from Alaska to the warm Hawaiian waters to mate and give birth. While you should never intentionally swim toward a whale—and federal law requires you to stay at least 100 yards away—it is not uncommon to hear their haunting songs while submerged. If you are snorkeling in a quiet area like the Molokini Crater or off the coast of Lanai, keep your ears open underwater; the acoustics of the ocean allow whale songs to travel for miles.
Winter Snorkeling Conditions
Snorkeling remains a top activity in December, but clarity can be an issue if there has been recent heavy rain or high surf. Runoff from the mountains can cloud the water near river mouths, particularly on the windward sides of the islands. To find the best visibility, aim for early morning excursions on the leeward (western or southern) sides of the islands. The Kona Coast on the Big Island often boasts the best visibility in the state during the winter due to its volcanic rock structure and lack of traditional soil runoff.
Practical Tips for December Ocean Activities
To ensure a successful swimming experience in December, a few practical considerations should be kept in mind. These tips focus on the local environment and the specific challenges of the season.
Reading the Conditions and Safety First
The most important rule in Hawaii is: “When in doubt, don’t go out.” The power of the Pacific Ocean is often underestimated by visitors. Even on a seemingly calm day, a “rogue” set of waves can arrive without warning. Always choose beaches with a stationed lifeguard. These professionals are experts in local conditions and will often post flags indicating the current hazard level.
In December, be particularly wary of rip currents. These are powerful channels of water flowing away from the shore, often found near breaks in the reef or at the ends of beaches. If you find yourself caught in one, stay calm, breathe, and swim parallel to the shoreline until you are out of the current’s pull.
Gear and Hazards
Sun protection is a year-round necessity. Even in December, the tropical sun is intense. However, many of the islands have passed laws banning sunscreens that contain chemicals harmful to coral reefs, such as oxybenzone and octinoxate. When preparing for your swim, ensure you use “reef-safe” mineral-based sunscreens or, better yet, wear a long-sleeved rash guard to minimize the need for lotions.
Additionally, be aware of the lunar cycle. Approximately 7 to 10 days after a full moon, certain beaches may experience an influx of box jellyfish. While usually not life-threatening, their stings are painful. Most popular beaches, such as Waikiki Beach, will have warning signs posted if jellyfish are present. Another minor hazard is the sea urchin, or “wana,” which hides in the crevices of the reef. Avoid stepping on the reef not only to protect the delicate coral but also to avoid a painful encounter with these sharp spines.
Embracing the Local Rhythm
Ultimately, swimming in Hawaii in December is about flexibility. You may find that your favorite beach from a previous summer trip is now a place for watching waves rather than swimming in them. By following the local advice, staying on the sheltered shores, and respecting the immense power of the winter swells, you can enjoy some of the most beautiful and refreshing swimming experiences found anywhere in the world. Whether you are floating in the calm lagoons of Oahu or watching sea turtles at Turtle Bay, the December waters offer a unique and invigorating perspective on the islands’ natural beauty.
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