Trade winds in Hawaii are a phenomenon that occur as a result of high pressure systems that form in the North Pacific. They are generally a very steady impact on the climate of Hawaii and bring a constant wind or breeze from the North East or East North East directions. As with changes of seemingly every other weather condition on the surface of the globe now days it appears that the trade winds in Hawaii are adjusting directions and decreasing in frequency. Where for years they came specifically out of the North East they are now adjusting to coming from a more Easterly direction and instead of buffeting the islands for perhaps 300 days a year they are now only providing about 220 days of wind. The velocity of the trade winds in Hawaii are not changing and they seem to stay steady at between 5 and 20 MPH throughout the year with the possible exception of September and October when they will generally decline somewhat in wind speeds. As these winds funnel through canyons and valleys on the islands they can also have increased wind speeds and these areas of the islands often have constant winds at much higher velocities.
Trade winds in Hawaii alter their course they are also predicted to lower the average rainfall over the island chain and as a result more drought conditions are expected as we move through the first half of the 21st century. This of course could have a dramatic effect on an island chain that continues to expand in population and has more and more need for this diminishing resource.
Kona Winds are the reverse of the trade winds in Hawaii. They blow from the opposite direction, the South West, and are usually caused by a nearby low pressure system in the North Pacific. Kona winds are less prevalent and whereas the Trades blow in the months surrounding the Summer season the Kona winds only blow in the Winter months primarily the months of January, February and March. Rain coming from a Kona storm can bring staggering amounts of inches of rain in a short period of time and since this rainfall hits that portion of the island that is usually dry it often proves to be quite dangerous as the island surface on the west and south sides is not as prepared to handle this type of deluge as the North and East coasts of the islands.
Trade winds in Hawaii account for 70% of all winds and are the most common winds over Hawaiian waters. These winds, which blow from a NE to ENE direction, became known as trade winds hundreds of years ago when trade ships carrying cargo depended on these easterly winds around the earth in the subtropics for speedy passage.
Trade winds in Hawaii prevail more than 90% of the time in the summer, sometimes persisting throughout an entire month. However, in the winter (January through March), trade winds in Hawaii may occur only 40% to 60% of the time. Though pleasantly brisk and refreshingly cool on land, strong, gusty trade winds in Hawaii can cause problems for mariners. Blowing from the NE through East direction, these strong trades funnel through the major channels between the islands at speeds 5-20 knots faster than the speeds over the open ocean.
Least windy time to visit
North Pacific high-pressure systems are responsible for the majority of gusty trade winds in Hawaii, which commonly persist for several days before tapering off. If you don’t like strong winds, visit Hawaii is in September and October. This is when the trade winds in Hawaii are usually at their lowest frequency.
What are Trade Winds Kona?
Kona winds is a Hawaiian term for the stormy, rain-bearing winds that blow over the islands from the SW or SSW in the opposite direction of trade winds. The western, or leeward sides of the islands, then become windward in this case, as the predominant wind pattern is reversed. Kona winds occur when a low-pressure center is within 500 miles Northwest of the Islands. Although strong Kona winds usually don’t last for more than a day or so.*
(*Information from the Pacific Disaster Center)