WILL MY FLIGHT
BE BUMPY?

What actually causes turbulence

Turbulence isn't one thing — it's several different phenomena that all produce the same stomach-dropping result. Understanding which type you're likely to encounter on your route is the first step to knowing whether to worry.

Clear air turbulence (CAT)

This is the most common type on long-haul flights and the hardest to avoid. It occurs at cruising altitude — typically 30,000 to 40,000 feet — with no visible warning. The main cause is the jet stream, a river of fast-moving air that circles the globe at altitude. Where the jet stream boundary meets slower-moving air, wind shear develops — adjacent layers of air moving at dramatically different speeds. That shear creates the invisible waves and eddies that shake the aircraft.

Transatlantic routes — particularly London to New York — cross the jet stream almost by definition, which is why North Atlantic flights are statistically among the bumpier routes in the world.

Convective turbulence

Caused by thunderstorms and strong updrafts. Pilots can usually see convective weather on radar and route around it, but flying near or between cells can still produce sharp jolts. This type is most common in summer afternoons over land, and over the tropics year-round.

Low-level wind shear (LLWS)

Occurs during approach and climb — the phases where most passengers notice bumpiness most acutely. A sudden change in wind speed or direction at low altitude creates an abrupt change in the aircraft's airspeed and lift. This is why the final minutes before touchdown on a windy day can feel rough even when the cruise was smooth.

Mountain wave turbulence

Air flowing over mountain ranges creates wave patterns that can extend hundreds of miles downwind. Routes crossing the Rockies, Alps, Andes, or Himalayas are more prone to this. Denver (DEN), Innsbruck, and Kathmandu are notorious for it.

How severe can it get

The aviation industry uses a standard scale from light to extreme. The vast majority of turbulence passengers encounter is in the light-to-moderate range — uncomfortable but not dangerous. Severe turbulence is rare, and extreme is exceptionally rare.

Which routes are worst

Some routes are structurally bumpier than others due to geography and the jet stream's path. These are consistently among the rougher routes in the world:

• LHR → JFK Crosses the North Atlantic jet stream head-on. Winter transatlantic flights are notoriously rough due to an accelerated jet stream.
• JFK → LAX Crosses the Rocky Mountains. The Midwest corridor generates consistent moderate turbulence, especially in winter.
• LHR → DXB Crosses mountainous terrain over Turkey and Iran. Often encountering jet stream on the outbound leg.
• SCL → EZE Buenos Aires to Santiago crosses the Andes — mountain wave turbulence is near-guaranteed on approach into Santiago.
• SYD → AKL The Tasman Sea route sits beneath the Southern Ocean jet stream — one of the strongest and most consistent on Earth.

That said, turbulence varies enormously by the specific day. A route that's usually smooth can be rough during a strong jet stream event, and vice versa. This is why checking the forecast for your specific date matters.

When is turbulence worse

Winter is generally worse than summer for CAT. The jet stream strengthens considerably in winter — speeds above 150 knots are not unusual — creating sharper wind shear at altitude. North Atlantic and North Pacific routes are meaningfully rougher from November through March.

Summer afternoons produce the worst convective turbulence. Afternoon thunderstorms over land — particularly in the US Southeast, Central Europe, and the tropics — create the most intense short-duration turbulence. Morning flights generally avoid this.

Time of day matters less for CAT since the jet stream is largely constant throughout the day, but convective cells tend to peak in late afternoon and dissipate overnight.

How to check your specific flight

The best forecasts for turbulence come from meteorological pressure-level data — the same data professional dispatchers use. The relevant models are ECMWF IFS (European Centre for Medium-Range Weather Forecasts), GFS (US National Weather Service), and the UK Met Office.

These models output wind speed and direction at multiple pressure levels (200hPa, 250hPa, 300hPa — corresponding roughly to cruising altitudes). Where adjacent layers show large differences in wind speed or direction, turbulence is likely. This is called vertical wind shear, and it's the primary numerical indicator used in Clear Air Turbulence scoring.

• 01 Check 12–24 hours before departure, not weeks in advance. Turbulence forecasts beyond about 3 days are unreliable. The night before or morning of your flight is the sweet spot.
• 02 Look at the en-route profile, not just the destination. The worst turbulence is usually mid-flight — particularly when crossing the jet stream. A smooth forecast at your destination says nothing about what happens at FL380 over the Atlantic.
• 03 Check low-level conditions for departure and arrival. Even if the cruise is smooth, strong winds at 2,000–3,000 feet — at your origin or destination — will produce bumpiness on climb and approach. Wind shear at 925hPa (roughly 2,600 feet) above 50 knots typically means a rough takeoff or landing.
• 04 A seat over the wing reduces perceived motion — the aircraft rotates around a point near the centre of gravity, so seats further from the wing (nose or tail) experience more vertical movement.
• 05 The seatbelt sign is not always on before turbulence hits. Clear air turbulence gives no warning on radar. Keep your belt loosely fastened whenever you're seated.

Frequently asked questions

Is turbulence dangerous?

For the aircraft, no. Commercial airframes are tested to extreme load factors far beyond what any turbulence event produces. The real risk is to unbelted passengers — the majority of serious turbulence injuries happen to people who were standing or had their belt off. Keep it on whenever you're seated.

Can pilots predict and avoid turbulence?

For convective turbulence (thunderstorms), yes — weather radar on board shows storm cells and pilots route around them. For clear air turbulence, prediction is harder. PIREPs (pilot reports) from aircraft ahead on the same route are shared in real time, and dispatchers use computer models to plan routes that minimise exposure. But CAT can appear with almost no warning.

Why does turbulence feel worse at the back of the plane?

The aircraft rotates around its centre of gravity, which sits near the wings. Seats further from this point — at the nose and particularly the tail — experience more vertical movement for the same amount of turbulence. Window seats also allow you to see the wings flexing, which can feel alarming but is completely normal.

Does rain mean a bumpy flight?

Not necessarily. Rain alone doesn't cause turbulence — the convective activity (updrafts and downdrafts) that generates thunderstorms does. Light rain at your destination is usually fine. Heavy showers, CAPE values above 500 J/kg, or weathercodes indicating convective activity are more meaningful indicators.

How accurate are turbulence forecasts?

For the next 12–24 hours, modern NWP models (ECMWF, GFS) are reasonably reliable for identifying regions of elevated CAT risk. Beyond 3 days, confidence degrades substantially. The forecast tells you the probability of encountering turbulence — not a guarantee, in either direction.