Temperature and Climate Zones
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.
Rainfall and Trade Winds
Through most of the year, Hawaiian weather patterns are affected
primarily by high-pressure zones in the north Pacific that pump
cool, moist trade winds down onto the island's northeastern slopes.
These winds are forced up-slope by the mountain heights where their
moisture condenses into clouds that produce rain. Most of the rain
falls in the mountains and valleys on the windward (northeastern)
side of the islands. It is this weather phenomenon that creates
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.
Hawaii's trade winds mean there is almost always a cooling
breeze here. Several times during the year the trade winds will
stop completely and the wind will switch around to come out of the
south or west, bringing stormy or hot sticky weather. Islanders
sometimes call this "Kona" weather, because kona means leeward or
South, and this points to the direction from which these weather
systems arrive.
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.
Hawaii's Mountains and Volcanoes
Many visitors are drawn to the natural beauty found in higher
elevations such as Kokee on Kauai, Haleakala on Maui, or Kilauea on
the Big Island. Temperatures in these higher locations drop 3.5
degrees for every 1,000 feet above sea level that you climb, so
dress appropriately with pants and several layers of clothing. At
an elevation of 10,023 feet, the summit of Haleakala can be as much
as 30º F. cooler than resort areas on the coast.
Also note that because of these high elevations, there is less
protection from the sun's powerful UV rays, so come prepared with
sun block and sunglasses.
