Hawaii - The Big Island: When to Go

Weather

The biggest climactic factor is location. On the leeward ( kona in Hawaiian) side, it's hot and dry, while the windward side is exposed to northeasterly trade winds that bring abundant annual rainfall. Occasionally, during kona weather, winds blow from the south, turning snorkeling spots into surfing spots and vice versa. Kona storms, which usually occur in winter, are very unpredictable. Kona winds also affect the movement of vog (volcanic smog). The climate also varies by elevation; the higher you go, the cooler and rainier it gets. In Volcano, at 1067m (3500ft), the average daily temperature in January is 18°C (65°F), with 4064mm (160in) of rainfall annually. At sea level in Hilo, the average temperature is 26°C (79°F) with almost 3302mm (130in) of rain per year, while in Kona it's 27°C (81°F) with only 1626mm (64in). Hotter and drier still is South Kohala, where Waikoloa receives under 254mm (10in) of rain per year (and Kawaihae's annual total might be only 76mm/3in). Seasonally, November to March is the rainiest period but on the windward side, monthly rainfall averages 254mm (10in). Still, only during storms does it rain all day. Even in Hilo you are almost sure to see some sunshine daily. Average temperatures on Hawai'i vary only mildly from winter to summer. In Waimea and Volcano, however, the weather is chilly, foggy, and often drizzly, which often surprises visitors. And if you plan to ascend the summit of Mauna Kea, be prepared for freezing temperatures.