We had a longer than usual spell of strong trade winds this December, so it might be helpful for those that don’t live here year-round to find out about our wind patterns.
Trade winds account for 70% of all winds in Hawaii 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.
During the summer, trades prevail more than 90% of the time, sometimes persisting throughout an entire month. However, in the winter (January through March), trade winds may occur only 40% to 60% of the time. Though pleasantly brisk and refreshingly cool on land, strong, gusty trade winds 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.
North Pacific high-pressure systems are responsible for the majority of gusty trade winds over Hawaiian waters, which commonly persist for several days before tapering off. Trade winds are usually at their lowest frequency in September and October.
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