The Most Turbulent Flight Routes, and Why They're Bumpy

Short answer: the bumpiest routes are the ones that cross big mountain ranges (the Andes, the Rockies, the Himalaya and the mountains of Central Asia), fly along strong jet streams (the North Atlantic and North Pacific, especially in winter), or pass through regions of frequent thunderstorms (the tropics, monsoon Asia, and the US South in summer). Even on these routes, most of the flight is usually smooth, and airlines fly all of them safely as a matter of routine.

Some routes are simply bumpier than others because of the geography and weather they cross. Knowing why helps you prepare, and helps you read a forecast for your own flight. We've grouped them by cause rather than ranking them: on any given day the order changes with the weather, which is what today's live rankings show.

Mountain Routes

When strong wind flows across a mountain range, it sets up waves in the air downwind, like water rippling over rocks in a stream. These mountain waves can reach cruise altitude and cause bumps well beyond the mountains themselves.

• Across the Andes: routes such as Santiago to Santa Cruz (Bolivia), and other flights over the central Andes, are known for mountain-wave bumps, especially in the southern winter when westerly winds are strong.
• The Rockies: flights in and out of Denver and Salt Lake City often feel mountain waves and gusty climbs and descents, particularly on windy winter days.
• The Himalaya and Tibetan Plateau: routes over and around the plateau, for example flights touching Chengdu or Kathmandu, meet both mountain waves and strong jet-stream winds.
• Central Asia: short hops across the Tian Shan, such as Almaty to Bishkek, can be bumpy for their length because the climb and descent happen right over the mountains.

Jet-Stream Corridors

The jet streams are rivers of fast wind at 30,000 to 40,000 feet. Where wind speed changes sharply above, below or beside them, clear-air turbulence forms, often with no cloud to show it.

• North Atlantic (New York, Boston or Toronto to London, Paris and beyond): the polar jet stream sits across this corridor, strongest from late autumn to early spring. Airlines often ride the jet eastbound for a faster flight, and that sometimes means passing through its bumpier edges.
• North Pacific (Tokyo or Seoul to the US West Coast): the jet stream over Japan is one of the strongest on Earth in winter, and transpacific routes regularly cross its edges.
• East Asia (for example routes around Japan, Korea and eastern China): the same winter jet affects shorter regional flights too.

Storm-Prone Regions

Convective turbulence comes from rising and sinking air in and around storm clouds. Pilots see storm cells on radar and route around them, so these bumps are usually brief, but they are more common in some places and seasons.

• The tropics: long-haul routes that cross the equator, such as Europe to southern Africa or South America, pass through the Intertropical Convergence Zone, a band of frequent storms.
• Monsoon Asia: routes over the Bay of Bengal and between India and Southeast Asia see more storms in the summer monsoon.
• The US South and the Gulf of Mexico: summer afternoon thunderstorms make flights in this region bumpier on climb and descent.

Seasonal Patterns

• Winter: stronger jet streams, so more clear-air turbulence on mid-latitude routes
• Summer: more thunderstorms over land, mostly in the afternoon and evening
• Monsoon season: more storm activity across South and Southeast Asia

For the full month-by-month picture, see when turbulence is worst.

Tips for Bumpier Routes

1. Book earlier in the day where you can: storms over land are less likely in the morning
2. Check the forecast for your actual flight: seasonal patterns are a starting point, but the day's weather decides your ride. Turbcast shows when in the flight any bumps are expected
3. Choose your seat: seats over the wing move the least (seat guide)
4. Keep your seatbelt fastened whenever you're seated: it is the one habit that matters most on any route

Conclusion

A route's reputation tells you what to expect on a typical day, not what will happen on your flight. Pilots on these routes know the patterns well, plan altitudes around them, and share reports with each other in real time. Expect some bumps, keep your seatbelt on, and let the crew do what they do on these routes every week.