Big Island Weather & Climate: A Year-Round Guide

The Island of Hawaiʻi, commonly known as the Big Island, is a meteorological marvel. It contains nearly all of the world's climate zones—ranging from tropical rainforests and arid deserts to polar tundra on its high summits. This diversity is driven by two massive volcanic peaks, Mauna Kea and Mauna Loa, which act as barriers to the persistent trade winds.

Typical Weather Patterns

Weather on the Big Island is primarily dictated by the northeasterly trade winds. These winds bring moisture-laden air from the Pacific, which hits the northeastern (windward) coast, rises, cools, and releases rain. This makes the Hilo side lush and tropical, while the western (leeward) Kona side remains largely dry and sunny, sheltered in the mountains' rain shadow.

Daily Climate Cycle

The island follows a predictable daily rhythm. Mornings are typically clear and sunny across most of the island. On the Kona side, as the land heats up during the day, it creates a thermal vacuum that pulls in moist sea breezes mid-afternoon, often resulting in cloud cover and short-lived upslope showers. Conversely, the Hilo side often experiences its heaviest rainfall at night and in the early morning hours.

Seasonal Trends

Hawaiʻi technically has only two seasons: Kau (summer) from May to October and Hoʻoilo (winter) from November to April.

• Summer (May–October): Characterized by stable trade winds and daytime highs between 85°F and 90°F (29°C–32°C). This is the sunniest time for most of the island, though humidity is higher. Hurricane season also falls within this window, peaking in August and September.
• Winter (November–April): Temperatures are slightly cooler, with highs averaging 78°F to 83°F (25°C–28°C). The primary change is the increased frequency of Kona Storms—low-pressure systems that reverse the wind direction to the southwest, bringing heavy rain and wind to the normally dry western coast.

Microclimates and Variations

The Big Island’s topography creates extreme variations over short distances:

• Hilo & Hamakua Coast: One of the wettest inhabited places on Earth, receiving over 130 inches of rain annually. It feels lush, damp, and vibrant.
• Kohala Coast & Waikoloa: The "Gold Coast" is a near-desert, receiving less than 10 inches of rain per year. It is consistently hot and dry.
• Waimea: Sitting at 2,600 feet, this "Upcountry" region is significantly cooler and often windier, with green rolling pastures that feel more like Ireland than a tropical island.
• The Summits: At nearly 14,000 feet, Mauna Kea and Mauna Loa can experience sub-freezing temperatures and snow even in mid-summer.

Local Phenomena: Vog and Laze

A unique feature of Big Island weather is Vog (volcanic smog), caused by sulfur dioxide emissions from Kīlauea reacting with sunlight and moisture. When trade winds are blowing, vog typically drifts toward the South Maui and Kona coasts, creating a hazy, grey-blue horizon. During "Kona wind" days, this haze may shift toward Hilo. Laze (lava haze) occurs when molten lava enters the ocean, creating a localized plume of hydrochloric acid and steam.

The "Feel" of the Weather

Beyond the thermometer, the Big Island is defined by its atmospheric weight. In the rainforests of Puna, the air feels heavy, sweet with the scent of damp earth and ginger. On the high slopes of Volcano Village, the air is crisp, thin, and carries the faint scent of sulfur. Because the surrounding ocean stays between 74°F and 80°F year-round, the coastal air never truly feels cold, but rather acts as a thermal blanket that keeps the nights balmy and the days soft.