Hawaii Weather and Rainfall

Hawaii’s weather can be quite confusing for those used to mainland weather patterns. The Big Island has 10 of the 15 types of the world’s climate. Hilo is the wettest city in the US, receiving more 130 inches of rain per year while Mt. Waialeale on Kauai gets the prize for being the 2nd wettest spot on earth, receiving more than 460 inches of rain per year. And yet Kekaha, only 20 miles SW of Mt. Waialeale, receives a scant 20 inches per year!

Temperatures

Hawaii, being in the tropics, has very consistent temperatures (at sea level). Summer time highs average 85 degrees while winter month highs average 78. The longest and shortest days are 13.5 and 11 hours long, and the UV index in the winter still gets into the 6-7 range (higher than Florida for example). The temperature drops by about 10-15 degrees at night. The water temperature ranges from about 74 in the winter to 81 in the summer. The warmest months are August and September.

Seasons

Hawaii only differentiates between two seasons: summer lasts from May – October and “winter” claims the rest of the year.

Ocean Consistency

The character of the ocean changes dramatically from season to season as far away storms in either the northern hemisphere (winter months) or southern hemisphere (summer months) send powerful waves to the north or south facing shores. The position of neighboring islands and reefs also greatly influence the surf that a beach is exposed to. Most northern beaches have a dual personality, often placid in the summer and very active in the winter with something in between in the spring and autumn. The same holds true for south beaches in the summer months, but the effect is less dramatic. East facing shores experience more consistent conditions, but both east and west are subject to wrap-around surf from the north or south depending on the shape of the island. Eastern shores are often active and choppy due to wind-waves from the trade winds.

Summary

Hawaii’s climate may represent the best the world has to offer, with shorts, a t-shirt and sandals appropriate year round. Some winter days do get cool, especially when it's windy and cloudy, so do pack a sweater and winter Pajamas. Summer temperatures almost never venture into the 90s (the highest recorded temperature was 100 degrees, in 1931). The rainfall yields lush tropical scenery, but is usually considerate enough to remain isolated and short lived.

The summer months (May-October) offer the optimal weather and one can safely ignore rainfall considerations in planning a trip (the Puna and Hilo regions of the Big Island require some extra consideration). For December through March, a dry region should be selected if sunshine is a major consideration, keeping in mind that the dry areas receive the bulk of their rain in the winter; that wetter zones are quite capable of experiencing plenty of winter sunshine; and that these zones are usually separated by less than an hours car ride.

Historic Rainfall and Temperature Data

Below we show each island's rainfall map and historic weather data for several towns so that you can get an idea of each area's micro climate. The data shown is the historic average rainfall and maximum temperatures for each month. Average nightime low temperatures are usually 10-15 degrees below the high. For in depth analysis and information visit the Western Regional Climate Center web site.

Oahu Rainfall and Temperatures

FYI, the town of Waialua is located next to Haleiwa, and the Ko Olina Resort is located on the coast SW of Kapolei. All tourist areas of Oahu have great micro climates, especially Waikiki. When the East coast is experiencing bad weather, head to Waikiki and watch the clouds miraculously disappear, stopped by the Koolau moutain range.

Oahu Rainfall Map

Maui Rainfall and Temperatures

No wonder Maui is so popular, all the tourists areas experience great weather all year round. Only Kapalua presents some fickle weather during the winter.

iPhone users, be sure to check out the Maui GPS Tour Guide, which includes surf and weather forecasts so you can plan your days while on island.

Maui Rainfall Map

Big Island Rainfall and Temperatures

The Big Island's east coast is known for it's wet weather, but that shouldn't disuade visitors particularly during the summer when much rain falls at night.

Big Island Rainfall Map

Kauai Rainfall and Temperatures

Many tourists prefer Kauai's south coast during the winter, although the North's beautiful scenery is hard to resist especially considering rainfall rarely lasts for long periods.

iPhone users, be sure to check out the Kauai GPS Tour Guide, which includes surf and weather forecasts so you can plan your days while on island.

Kauai Rainfall Map