What Are Trade Winds In Hawaii?

The consistent breezes that keep Hawaiian islanders cool in the tropical climate are known as trade winds. If you’re short on time, here’s a quick answer to your question: Trade winds in Hawaii are steady east-to-northeast winds that regulate the weather throughout the islands.

Read on for a deep dive into the causes and characteristics of Hawaii’s famous trade winds. You’ll discover where trade winds originate, why they developed, what path they take to reach Hawaii, how they help shape the islands’ climate and weather, and the influence they have on surf conditions across the state.

The Origin and Development of Trade Winds

Causes Behind Trade Wind Formation

Trade winds originate from the differences in air pressure between the equator and the poles. At the equator, the Sun heats up air molecules, causing them to expand and rise. This creates an area of low surface air pressure.

At the poles, the air is much colder, causing air molecules to contract and sink, creating high surface air pressure.

Air flows from areas of high to low pressure. So in the atmosphere, air flows poleward from the equatorial low pressure zone, and toward the equator from the polar highs. But because of the Coriolis effect from Earth’s rotation, winds get deflected off course, blowing at an angle instead.

The end result are the famous trade winds that blow from the subtropical highs toward the equatorial low.

Global Air Circulation Patterns

The trade winds are part of Earth’s large-scale air circulation cells. There are three primary circulation cells – the Hadley cells, Ferrel cells, and polar cells.

The Hadley cells extend from the equator to about 30° latitude in both hemispheres. Within them, warm tropical air rises at the equator, flows poleward, cools, then sinks back down around 30° and returns equatorward along the surface.

The poleward part gives the prevailing tropical easterlies, or trade winds.

At midlatitudes around 30-60° lies the Ferrel cells. In them, cool air sinks and flows equatorward along the surface, causing the subtropical highs and trade winds. Upon reaching the subtropics around 30°, the air warms and rises, moving poleward aloft.

Eventually it cools and sinks over the poles, completing the Ferrel circulation cell.

Trade Winds’ Journey to Hawaii

Crossing the Pacific Ocean

The trade winds originate near the Horse Latitudes where hot air rises at around 30 degrees North and South. As this air rises, cool air flows in from the north and south to replace it. This cool air flows toward the equator and picks up speed, powered by the Coriolis effect, becoming the trade winds.

These reliable winds blow from the northeast in the Northern Hemisphere and the southeast in the Southern Hemisphere. Loaded with moisture evaporated from the oceans, the trade winds journey thousands of miles across the Pacific Ocean on their way to Hawaii.

It’s amazing how these winds can travel such vast distances over open water, driven by the global atmospheric circulation. As they near Hawaii, the winds have built up quite a head of steam, averaging 10-20 mph as they approach the islands.

Interactions with Hawaii’s Volcanic Peaks

Hawaii’s volcanic peaks rise abruptly from the sea floor, presenting a formidable barrier to the rushing trade winds. The winds blow up the slopes, cooling as they rise in altitude. This cooling causes moisture to condense and fall as rain on the windward sides of the islands, creating lush tropical rainforests.

For example, Mount Waialeale on Kauai receives over 460 inches of rain per year, making it one of the rainiest spots on Earth! Meanwhile, the leeward sides remain much drier, with desert-like conditions.

The trade winds also shape Hawaii’s world-famous beaches. On windward shores, waves churned up by the winds deposit sand gradually, forming wide, sandy beaches. Leeward shores guarded from the winds have fewer waves and little sand accumulation.

From rainfall to recreation, it’s clear that Hawaii’s iconic environment owes much to the far-reaching effects of the remarkable trade winds blowing all the way from the distant Horse Latitudes.

Effects of Trade Winds on Hawaii’s Climate

Consistent Breezes

The northeast trade winds blow consistently towards the Hawaiian islands for the majority of the year, providing a cooling and comfortable breeze. These winds average 12-20 mph, though can reach up to 30 mph at times.

The consistency of the winds leads to ideal weather for surfing, sailing, kiteboarding and other ocean activities that rely on steady winds.

Weather Regulation

The trade winds play a key role in regulating Hawaii’s tropical climate and keeping temperatures pleasant all year long. As the winds blow over the ocean, they pick up moisture and keep the islands humid. However, the winds also block full exposure to the harsh tropical sun.

This combination creates an enjoyable tropical climate that draws over 10 million visitors per year.

According to the Hawaii Tourism Authority, over 85% of visitors surveyed were very satisfied with Hawaii’s tropical climate and temperatures.

Rainfall Patterns

The trade winds produce unique rainfall patterns across the Hawaiian islands. As moist winds blow up the mountains, water vapor condenses and falls as rain on the windward mountain sides. For example, over 460 inches of rain can fall yearly on the windward side of the Big Island’s tallest peak, Mauna Kea.

Meanwhile, the leeward sides sit in a rain shadow and receive little precipitation. This explains why west Maui averages under 15 inches of rain yearly while east Maui receives over 360 inches on essentially the same latitude.

The hilly topography combined with consistent winds makes Hawaii the only state with such incredibly diverse microclimates and vegetation within relatively tiny distances.

Impacts on Surf Conditions and Ocean Sports

Surf Size and Consistency

The consistent trade winds blowing from the northeast have a significant impact on surf conditions across the Hawaiian Islands. As the winds travel across thousands of miles of open ocean, they whip up large swells that approach from the north and east.

This creates ideal surf on north and east facing shores during the summer when the trades are most persistent. Famous spots like Pipeline, Sunset Beach, and Waimea Bay on Oahu’s North Shore see surf consistency upwards of 300 days per year thanks to the trades (see SurferToday).

Swell size generally ranges from 4-8 feet, with larger surf when storms pass through the trade wind belt.

The trades also shelter south and west facing shores from ocean swell, creating smaller surf conditions favored by beginner and intermediate surfers. However, when the winds ease periodically from April to October, it allows southern hemisphere swells to wrap in and light up spots like South Shore Pipeline and Honolua Bay on Maui’s northwest coast.

Windsurfing and Kitesurfing Hotspots

Hawaii’s steady trade winds have also earned it a reputation as a top windsurfing and kitesurfing destination. Maui is considered the windsurfing capital of the world. The wind blows side or side-on shore along Maui’s north shore allowing for speed and jumping, while side-off shore winds on the south shores around Kihei create smooth sailing conditions.

The famous Hookipa Beach on Maui’s north shore sees wind speeds up to 30 knots attracting wave sailors from around the world (see live wind speeds at WindAlert).

For kitesurfing, the strongest wind and best conditions are found on Oahu’s east shores around Kailua Beach and Makapuu Beach where side or side-onshore winds can drive riders up to 30 mph. Kiteboarders also flock to Kite Beach on Maui’s south shore which lives up to its name with side-off shore winds peaking around 25 knots in the summer season.

Occasionally when the trades ease off, conditions can also turn on at spots like Kanaha Beach Park for flat water freestyle kiteboarding moves. So whether you’re a surfer, windsurfer or kiter, Hawaii’s trusty trade winds offer diverse conditions to progress and have fun in your ocean sport all year round!

Conclusion

Trade winds have shaped nearly every aspect of Hawaiian life over the centuries, from the climate to surf spots to agricultural practices and more. As steady breezes sweeping eastward across thousands of miles of open ocean, they bring relatively stable weather patterns that islanders have come to rely on.

Though early Hawaiian settlers adapted their lifestyle around consistent trade wind patterns, the winds remain an ever-present reminder of the islands’ remote location in the vast Pacific. Modern-day residents, visitors, and ocean sport enthusiasts still welcome the cooling trade wind breezes in Hawaii’s tropical climate.

Sharing is caring!