Weather intensity along the Road to Hana can be inversely proportional to your fun factor on this Maui adventure. The weather can be predictable if you know a few things first and plan ahead. Rain will be your biggest weather worry. There are 4 ways in which Maui’s weather delivers rain along the Road to Hana, Trade-Winds & Topography, Cold Fronts, Shear Lines and Tropical Storms. Knowing a little about Maui’s weather and checking the forecast can help you plan your Road to Hana adventure to be a huge success.
Rainy Weather Produced by Trade-Winds & Topography
The Road to Hana traverses Maui’s windward Eastside which is the watershed for the island. Of the 7 climatic regions of Hawai’i, this area is categorized as “Windward Lowlands, a region lying more or less perpendicular to the prevailing flow of the trade winds, is moderately rainy, and has frequent trade-wind showers. Partly cloudy to cloudy days are common.
Prevailing trade-winds from the northeast causes warm tropical moist air to blow up the east slopes of the dormant volcano Haleakala, rise, cool, condense and precipitate over Maui’s east side including the Road to Hana. Hence, lots of rainfall, a tropical rainforest and numerous fresh water pools and waterfalls along the way.
Rainfall intensities can range from mist or drizzle, to light or moderate. It is not uncommon to have up to ten brief showers in a single day, none of which being heavy enough to produce 0.01 inch of rain.
This type of rain is more common than storm systems and it should not detour you from your Road to Hana adventure. The rainfall, drizzle or mist will most likely pass quickly with the prevailing trade winds and the sun can be around the next curve. It also rains most every night here, so if you are on the Road to Hana before 9 or 10 am and you have some rain, keep going, it is most likely the remnants of the nightly rainfall and should stop soon.
Rainy Weather Produced by Cold Fronts (Extratropical Cyclone)
Kona Storms (Kona Lows) are cold front cyclones which come from the leeward or westerly direction, and can affect Maui up to 2-3 times a year in the winter months between October and April. The duration of a Kona Storm can be as long as 1 week and typically bring torrential rainfall, flash floods, landslides, high surf and water spouts to the island of Maui.
Rainy Weather Produced by Shear Lines
Areas of low pressure far away to the Northeast can produce a shear line. Moisture is concentrated into a narrow region in front of the cold front and produces a long tail that can reach from Hawai’i to the Pacific Coast of the mainland U.S. This is also known as the atmospheric river condition known as the “Pineapple Express”. Shear lines can bring widespread rain to Maui.
Rainy Weather Produced by Tropical Storms and Hurricanes (Tropical Cyclone)
Occasionally, weather on Maui can bring tropical storms and on rare occasions hurricanes. Tropical storms (cyclones) can produce extremely powerful winds and torrential rain, flash flooding along with high surf, storm surge, waterspouts and tornados. An average of 4-5 tropical cyclones affect Hawai’i each year from July to November. Check the Central Pacific Hurricane Center for information on tropical storms and hurricanes affecting the island of Maui.
Planning Ahead for Weather
During Kona, Shear Line or Tropical Storm systems, the Road to Hana journey is best postponed until better weather. The waterfalls will be at their peak; however, viewing, hiking to, and photographing them will be miserable. Pools will also be at peak elevation and dangerous for swimming. Haleakala National Park in Kipahulu will close the ‘Ohe’o Gulch pools and Pipiwai Trail falls and pools to all swimming during and after heavy rainfall for safety reasons. Heavy Kona and Tropical Storms can guarantee flash flooding and danger.
On most days, the clouds blow through quick and you can experience rain off and on while on the Road to Hana. Check Radar, Satellite and Forecast weather reports before you commit to the long drive. Give weather Radar and Satellite links a moment to load, they are loops which will give you the best current information.