Hawaii Weather In December Temperatures And What To Expect
December in Hawaii marks the transition into the heart of winter, bringing a distinct shift in weather patterns driven by the state’s dominant trade winds and the influence of the Pacific Ocean. This month serves as the official start of the state’s rainy season on most islands, particularly on the windward, or eastern, sides of the islands where rainfall is most concentrated. While the days remain warm and largely inviting, travelers and residents alike must prepare for increased humidity, more frequent showers, and the occasional impact of passing cyclones on the broader Pacific weather systems.
For the traveler seeking a tropical escape, December offers a compelling blend of warm temperatures and lush scenery, though it requires a nuanced understanding of regional variations across the archipelago. From the bustling resort hubs of Waikiki to the rugged peaks of Maui’s Haleakalā, the weather in December is far from uniform, with microclimates dictating everything from rainfall totals to daily sunshine hours. This guide provides a detailed breakdown of what to expect, combining meteorological data with practical advice for those planning visits or extended stays during this vibrant season.
Temperature Trends Across the Islands
Average daytime high temperatures in Hawaii during December typically range from the mid-70s to low-80s Fahrenheit (around 24–28°C), depending largely on elevation and island location. Coastal areas, especially those on the leeward, or western, sides of the islands, generally enjoy the warmest and most consistent conditions, making them popular destinations for sun-seeking visitors. Honolulu, for example, often records average highs near 80°F (27°C), with lows rarely dropping below 65°F (18°C), creating an environment that supports outdoor activities nearly every day of the month.
Temperature Variations by Island
Each of the main Hawaiian Islands experiences December temperatures with subtle but important distinctions:
Oahu: Honolulu and Waikiki maintain relatively stable temperatures, with averages hovering around 80°F (27°C) during the day and 65°F (18°C) at night. The North Shore, while cooler and notably wetter, rarely sees temperatures below 60°F (16°C).
Maui: The island’s diverse topography creates striking temperature contrasts. Coastal resorts in Kihei and Wailea enjoy warmth similar to Oahu, while upcountry regions such as Makawao and Kula experience noticeably cooler evenings, sometimes dipping into the 50s°F (10–15°C). Atop Haleakalā, temperatures can resemble winter conditions elsewhere in the U.S., often falling below freezing and dusted with rare snowfall.
Big Island: In Hilo, on the windward side, average highs reach about 82°F (28°C), with consistently higher humidity and rainfall. Kailua-Kona, on the leeward side, offers warmer and drier conditions, with temperatures frequently reaching the mid-80s°F (29–30°C) and minimal rain.
Kauai: Lihue follows similar patterns to Hilo, with warm but humid conditions and substantial rainfall on the east side. The west side remains more favorable for outdoor plans, with temperatures in the low 80s°F (27–28°C) and fewer showers.
Molokai and Lanai: These smaller islands experience moderate temperatures, with averages in the low 80s°F (around 27°C). Their relatively small size means less dramatic variation, though windward areas remain wetter year-round.
Precipitation and Humidity
December is the beginning of the rainy season for most of Hawaii, particularly for the windward coasts of Kauai, Oahu, Maui, and the Big Island. These areas are directly exposed to the prevailing northeast trade winds, which push moist ocean air inland, where it cools, condenses, and falls as rain. The phenomenon creates dramatic contrasts, where a resort area can be sunny while just a few miles away, a rainforest is experiencing a steady downpour.
Monthly Rainfall Averages (Windward vs. Leeward)
To illustrate these differences, consider the following approximate monthly rainfall averages:
Windward Coast (e.g., Hilo, Kaneohe, Hana): 15 to 25 inches (380–635 mm) of rain.
Leeward Coast (e.g., Kailua-Kona, Kihei, Lahaina): 2 to 6 inches (50–150 mm) of rain.
Mountain Summits: Haleakalā and Mauna Loa can receive significant rainfall, with some elevations recording over 40 inches (1,000 mm) for the month.
These numbers are not uniform from year to year, as atmospheric patterns such as El Niño or La Niña can shift rainfall totals significantly. During strong El Niño events, for example, Hawaii tends to experience drier conditions, while La Niña often enhances rainfall, particularly on the windward sides.
Humidity in December averages between 60% and 80% across most populated areas, often feeling higher in the mornings and late afternoons when trade winds subside. The combination of warmth and moisture can make temperatures in the upper 70s feel considerably warmer, especially in urban centers where heat retention from concrete and asphalt amplifies the effect.
Sunshine, Clouds, and Daylight
Despite the increased likelihood of rain, December still offers ample sunshine across much of the islands. Honolulu, for instance, averages about 7 to 8 hours of sunshine per day during the month, with roughly 65% of possible daylight hours seeing direct sun. This is largely due to the movement of the Pacific high-pressure system, which often pushes storm systems north or south of the main islands, allowing for intermittent clear skies between showers.
Sunrise and Sunset Times in December
Sunrise in Honolulu occurs around 7:10 a.m., while sunset is near 5:45 p.m., providing approximately 10 hours and 35 minutes of daylight. Days grow slightly shorter as the month progresses, with daylight decreasing by about 3 minutes by New Year’s Day. This gradual shift is less noticeable in tropical locations than in temperate climates, but it contributes to the subtle change in the quality of light, especially in the late afternoon.
Cloud cover in December is typically variable. Morning skies are often clear, with clouds building in the afternoon as daytime heating triggers localized showers. On windward slopes, cloud layers can persist for hours, creating a cool, misty environment even at lower elevations. Leeward areas, by contrast, may enjoy mostly cloud-free conditions, with cloud formation occurring only in the evening as temperatures drop.
Ocean Conditions and Coastal Weather
The Pacific Ocean remains relatively warm in December, with surface temperatures ranging from 75°F (24°C) in the far northwestern islands to 78°F (26°C) in the south. These temperatures make swimming and water activities comfortable, though ocean conditions can vary significantly based on location and exposure.
What to Know About Ocean Safety
North Shore beaches on Oahu, famous for massive winter swells, experience powerful surf that can be hazardous even for experienced swimmers. Visitors are strongly advised to respect warning signs and swim only at lifeguarded beaches. On Maui and the Big Island, southern and western coasts tend to be calmer, with smaller, more manageable waves.
Rip currents remain a year-round concern, but they are particularly prevalent during the winter months when storm systems generate stronger longshore currents. Swimmers should always check local conditions, avoid entering the water after heavy rains, and be aware of warning flags posted at beach accesses.
Planning Your Visit or Daily Routine
Understanding Hawaii weather in December allows for better preparation, whether you are packing for a vacation or planning daily activities. Clothing should be versatile, accommodating warm days, cool evenings, and the possibility of rain. Lightweight, breathable fabrics work well during the day, while a light jacket or sweater is advisable for nighttime outings, especially at higher elevations.
Practical Tips for Travelers and Residents
Pack waterproof gear: A compact umbrella and a rain jacket are essential, particularly if you plan to explore windward areas or go hiking.
Protect electronics: Humidity and sudden rain showers can affect devices; waterproof cases or bags provide an added layer of protection.
Schedule flexible outdoor plans: Build in buffer time for travel between locations in case of weather-related delays.
Check local forecasts: Conditions can vary greatly over short distances; a morning forecast for Honolulu may not apply to Hana or Waimea.
Respect the ocean: Always follow safety guidelines, heed lifeguard advice, and avoid entering the water during high surf advisories.
For residents, December often means adjusting routines to accommodate wetter commutes and the potential for minor flooding in low-lying areas. Gardeners should protect sensitive plants from heavy rain and cooler nighttime temperatures, while outdoor event planners should have contingency plans in place.
When Weather Patterns Shift
Hawaii’s weather is influenced by large-scale climate patterns that extend beyond the daily forecast. The El Niño-Southern Oscillation (ENSO), for example, plays a significant role in determining whether a December will be wetter or drier than average. During El Niño years, the jet stream shifts southward, often pushing storm systems away from the islands and resulting in below-average rainfall. La Niña years, conversely, tend to enhance trade wind strength and moisture flow, leading to increased rain totals, especially on windward slopes.
These broader climate interactions remind residents and visitors alike that while general trends are reliable, local conditions can change quickly. Staying informed through trusted weather sources, such as the National Weather Service or local meteorological agencies, helps ensure that plans align with the actual conditions on the ground.
Embracing the December Atmosphere
Despite the increased rain and occasional cloud cover, December remains one of the most atmospheric times to be in Hawaii. The islands take on a deeper green as winter rains nourish the land, waterfalls gain strength, and native plants burst into seasonal blooms. For those willing to adapt to the rhythm of passing showers, the season offers a more intimate connection to Hawaii’s natural cycles, away from the peak tourist crowds of spring and summer.
Whether watching a sunrise break through clouds over Diamond Head or listening to the steady rain on a lanai in Hilo, December weather invites a slower, more attentive engagement with the environment. Understanding the nuances of temperature, precipitation, and ocean conditions allows residents and visitors to move through the month with confidence, ready to enjoy the best that Hawaii’s winter season has to offer.
