Weather in Hawaii is very consistent, with only minor changes in temperature throughout the year. There are really only 2 seasons in Hawaii: summer (called Kau in Hawaiian) from May to October and winter (Hooilo) from November to April. The average daytime summer temperature at sea level is 85º F. (29.4 C) while the average daytime winter temperature is 78º (25.6º C). Temperatures at night are approximately 10º F. lower.
The islands are an incredible collection of diverse micro-environments, each with its own unique weather, plants, and animals. As a result of the shielding effect of volcanic mountains and the differences in weather found at various elevations, you can find tropical rain forests, cool alpine regions, arid deserts, and sunny beaches - all within the span of just a few miles.
Water and Surf Conditions
Hawaii's near-shore water temperatures remain comfortable throughout the year. The average water temperature is 74º F. (23.3 C), with a summer high of 80º F. (26.7º C). Wave action varies dramatically between island coasts and seasons. Summer waters are typically gentle on all beaches. During the winter on many north shore beaches, Pacific storms drive ocean swells towards the islands, creating Hawaii’s legendary big waves.
Wave conditions are often very localized, so if the waves are too big on your beach, you can usually find calmer water at a more sheltered beach. Strong currents can make any beach unsafe at any time during the year, particularly in the winter. Ask your hotel staff or a lifeguard about ocean currents or look for warning flags and posted beach conditions.
Most of the rain falls in the mountains and valleys on the windward (northeastern) side of the islands. It is these passing showers that create Hawaii’s rich, green, tropical environment.
The wettest months are from November to March, but winter rains do not generally disrupt vacation plans, since the weather is very localized. This means that if it is raining where you are, there is almost always a sunny spot to be found around the coast.
In Hawaii, we are fortunate to enjoy the comfortable weather cooled by the trade winds. Named for the winds that once carried ships around the globe, these gentle breezes keep our island weather just right during most of the year, but can become gusty and dangerous on occasion.
From January through March, the trade winds are less frequent and the islands experience the humid conditions referred to as "Kona weather." Kona winds is the local term for stormy, rain-bearing winds. Under extreme conditions, Kona winds can cause extensive damage.
Please heed all weather warnings before hiking, swimming, sailing, or participating in any outdoor activities.
Vog is the local term for "volcanic fog" and it describes the hazy air pollution that occasionally hangs over the islands. Vog is caused when sulfur dioxide and other gasses from Kilauea's Halemaumau Crater (Big Island of Hawaii) mix with moisture in the air and sunlight. Under extreme conditions—when the volcano is active and the winds carry the fumes north to the rest of the island chain—vog can be hazardous to plants, animals and humans. The most common effects are headaches, watery eyes and breathing difficulties. These effects can be especially pronounced in people with respiratory conditions and young children. It is not advisable to exercise or participate in strenuous outdoor activities when the vog is very heavy. Depending on your personal sensitivity, you may want to learn more about vog before traveling to Hawaii Island and visiting Hawaii Volcanoes National Park.
Want to know what the vog conditions are around the island? Check your local news weather report.
Not all hazy conditions are caused by vog. If you see a white mist along the coast, it could simply be salt spray hanging in the air. Or if it's hazy along the mountains in the morning, chances are you're looking at moisture in the air from the updrafts along the ridges.
Hawaii's Mountains and Volcanoes
Many visitors are drawn to the natural beauty found in higher elevations. While a light jacket and casual clothes will serve you for most of your trip, you will need warmer clothing if you plan to hike Haleakala on Maui where the temperatures average 40°F- 60°F (5° - 16°C). On Maunakea on Hawaii Island it can get as cold as 12° F (11°C) after sundown. Mountain campsites such as Kokee State Park and Hawaii Volcanoes National Park can also be extremely chilly so check with park officials before camping.