Hawaii December Weather: Temperature, Trade Winds, and Rainfall Averages Across the Islands

December in Hawaii marks the official arrival of winter, bringing slightly cooler temperatures, increased rainfall, and reliably moderate trade winds. While still comfortably warm by global standards, the month introduces a noticeable shift from the long, dry stretch of late spring through early fall. This article provides a detailed, fact-focused overview of what to expect across the Hawaiian Islands during December, drawing on long-term climate normals and expert meteorological insights.

The primary driver behind Hawaii’s December weather pattern is the seasonal shift of the Pacific subtropical high and the intensification of the winter storm track in the North Pacific. These changes influence the strength and direction of the steady easterly winds and can enhance orographic rainfall, particularly on island windward slopes. For visitors and residents alike, understanding these dynamics helps set realistic expectations for sunshine, showers, and overall conditions from Oahu and Maui to Kauai and the Big Island.

Hawaii benefits from a maritime tropical climate moderated by the surrounding ocean, which keeps extreme temperature swings uncommon even during the year’s coolest month. December averages serve as a practical baseline for planning outdoor activities, travel logistics, and packing decisions, though day-to-day variability remains important to consider. As Dr. Timothy Workman, a climate specialist with the National Weather Service in Honolulu, explains, “December is part of our cooler and wetter season, but the islands remain warm. The key is understanding where and when rain is most likely, rather than expecting uniform conditions across all regions and elevations.”

Across most of Hawaii, December daytime high temperatures typically range from the mid-70s to low-80s Fahrenheit, or around 24 to 28 degrees Celsius, depending on location and exposure. Coastal lowland areas, especially on leeward sides, often see daytime highs near 80 degrees, while cooler elevations and eastern slopes may stay in the mid-70s or lower at higher altitudes. Nighttime lows usually fall between the mid-60s and low 70s Fahrenheit, or approximately 18 to 22 degrees Celsius, with some mountain and high-elevation valleys occasionally dipping into the 50s during clear, calm nights.

These averages, compiled from decades of data by the National Centers for Environmental Information and local climate monitoring programs, show that December is notably cooler than the summer peak in August, yet still mild compared to most other U.S. locations at similar latitudes. For example, while parts of the U.S. mainland are experiencing freezing temperatures or early winter storms, Honolulu seldom sees temperatures below 60 degrees Fahrenheit. The surrounding Pacific Ocean acts as a massive thermal buffer, limiting extreme cold and keeping conditions consistently pleasant, even during the rainier months.

Island-specific variations are pronounced and worth noting for anyone planning island-hopping or outdoor excursions. On Oahu, December often brings comfortable temperatures in Honolulu and Waikiki, with average highs near 80 degrees, while windward areas such as Kailua may see more frequent rain and slightly cooler conditions. Maui’s windward coast around Hana experiences significantly higher rainfall than the leeward resort areas of Kihei and Wailea, illustrating how topography shapes local weather. On Kauai, the north shore and Mount Waialeale can be exceptionally wet in December, while the south shore remains relatively drier, and the Big Island shows a sharp contrast between the leeward Kona coast and the windward Hilo side, where showers are more common.

Rainfall in December tends to increase across the islands compared to the late spring through fall drought period, largely due to more frequent winter storms and enhanced moisture flow. While not as intense as the peak winter months of January and February, December still contributes meaningfully to the annual precipitation total, especially on windward slopes where orographic lifting encourages cloud formation and showers. Trade winds, which blow predominantly from the northeast, are generally steady and noticeable, creating a refreshing breeze along coastal areas but also channeling moist air upward over mountain barriers, leading to concentrated rainfall in certain zones.

Wind patterns in December are typically characterized by moderate to fresh trade winds, with average speeds ranging from 10 to 20 miles per hour at lower elevations and often increasing at higher altitudes. On exposed ridges, summits, and coastal areas, winds can occasionally reach gale force during the passage of a strong cold front or tropical disturbance, though such events are relatively uncommon. These brisk winds contribute to a lower feels-like temperature, particularly in the evening, making a light windbreaker or long-sleeve shirt a practical addition to beach gear even when daytime warmth persists.

For travelers, December remains a popular time to visit Hawaii, offering a balance of pleasant weather, fewer crowds than the peak winter holiday period, and reasonable rates before the busiest season ramps up in late December. However, conditions can vary significantly within a single island, and even within a single day, depending on location and elevation. Travelers heading to windward coasts, such as the Hana Highway on Maui or the eastern shores of Kauai, should anticipate rain showers and plan indoor activities or flexible itineraries accordingly. Those focused on leeward resorts and urban centers can generally expect mostly sunny conditions with occasional brief showers, providing ample opportunity for beach time, hiking, and sightseeing.

Understanding daily and weekly fluctuations requires attention to regional weather forecasts and advisories from official sources, including the National Weather Service offices in Honolulu, Honolulu County, and specific island locations. These agencies provide detailed outlooks that highlight the likelihood of showers, wind shifts, and any elevated weather hazards such as high surf, rip currents, or localized flooding in areas with steep terrain and intense rainfall. Taking a few minutes to review the forecast for the specific areas you plan to visit can make a significant difference in both safety and enjoyment.

In summary, Hawaii in December offers a reliably warm and moderately wet climate across its major islands, shaped by seasonal trade winds, shifting storm tracks, and diverse topography. While temperatures remain comfortable compared with most other destinations at this time of year, rainfall and wind conditions vary noticeably between windward and leeward areas, as well as at different elevations. For those prepared with realistic expectations and flexible plans, December can provide an ideal window to experience Hawaii’s natural beauty, outdoor recreation, and cultural offerings at a relaxed pace.