Portland Maine to Kona Turbulence Forecast

PWM → KOA · 5,080 miles · ~10h 40m

What to Expect

Portland to Kona is a long, west-bound flight that crosses a wide variety of geographic features, each with its own potential for turbulence. Shortly after takeoff, you might experience some light mechanical turbulence as you cross the Northern Appalachians. As you head west, crossing the Great Lakes could bring some lake-effect turbulence, especially if the air temperature is much colder than the relatively warmer lake water. Further west, over the Upper Midwest and Great Plains, clear-air turbulence, or CAT, is possible, caused by shifting air currents at high altitudes. As you approach the Northern Rockies and the Sierra Nevada, mountain wave turbulence could occur as the wind interacts with the mountains. Finally, over the Pacific, oceanic clear-air turbulence and some oceanic convection are common, but these are usually mild. Pilots are trained to anticipate and navigate these conditions, constantly monitoring weather patterns and adjusting altitude as needed.

The Portland Maine to Kona route crosses the Northern Rockies, a rugged expanse of high peaks in Montana, Idaho, and Wyoming. Mountain wave turbulence is frequent here, especially when Pacific storm systems push strong winds over the Continental Divide. Pilots often report moderate chop between 30,000 and 40,000 feet over this region.

Turbulence Factors on This Route

• Clear-Air Turbulence (CAT): The Atlantic coast jet stream and land-sea temperature contrasts create frequent clear-air turbulence at cruising altitude.
• Mechanical Turbulence: The Northern Appalachians generate low-level mechanical turbulence during strong post-frontal northwest winds.
• Lake-Effect Turbulence: The Great Lakes produce lake-effect convection and low-level wind shear from land-water temperature contrasts.
• Mountain Wave Turbulence: The Northern Rockies generate powerful lee waves when Pacific fronts drive westerly flow across the high terrain.

When Is This Route Bumpiest?

For the smoothest possible ride, aim to fly this route in the summer or early fall. Spring and early summer also tend to be smoother than other times of year. Winter, late fall, early winter, and early spring tend to be the bumpiest. This is because the temperature differences between air masses are greater during those times of year. These temperature differences lead to more turbulence, especially clear-air turbulence over the plains and mountain wave turbulence near the Rockies and Sierra Nevada. Late summer can also be a bit bumpy at times.

Tips for This Flight

If possible, try to book a morning flight, as turbulence tends to be less common earlier in the day. Any turbulence you encounter on this route will likely feel like driving on a bumpy road or the sensation of a small boat gently rocking on the water; it's usually more of an annoyance than anything alarming. For extra comfort, choose a seat over the wing, as this area experiences less motion. Remember to stay hydrated and practice deep, slow breathing. Know that the pilots are highly skilled at handling these situations, and you'll be in good hands.

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Forecasts based on NOAA HRRR and GFS atmospheric model data.