What Is the Jet Stream in Aviation?
Sources: NOAA, WMO, ICAO · Updated May 2026
The jet stream is a narrow band of fast west-to-east wind at the top of the troposphere — roughly 9 to 12 km altitude (FL300 to FL400), exactly the cruise band of commercial jets. Typical jet-stream speeds are 80-140 mph (130-225 km/h); winter peaks can exceed 200 mph (320 km/h), and NOAA has recorded extremes near 275 mph (440 km/h). The northern hemisphere has two main jets: the polar jet (about 50-60°N, the stronger and most aviation-relevant) and the subtropical jet (about 30°N). Both shift seasonally. Aviation interacts with the jet stream in two ways: eastbound flights ride it for a 30-90 minute saving on a transcontinental crossing; westbound flights detour to avoid the headwind. Pilots also watch for clear-air turbulence near the jet stream boundaries.
How a jet stream forms
The atmosphere is heated unevenly: tropical regions absorb more solar energy than the poles. This temperature difference drives meridional (north-south) circulation cells, and conservation of angular momentum turns much of that motion into west-east wind. The temperature contrast is sharpest near the tropopause — and the strongest winds appear right at that level, concentrated into a narrow ribbon called a jet stream.
The polar jet sits at the boundary between cold polar air and warm mid-latitude air; the subtropical jet sits at the boundary between mid-latitude and tropical air. Both follow meandering, looping paths (the "Rossby waves") rather than straight circles around the planet.
Polar jet vs subtropical jet
Latitude 50-60°N (and S), altitude 9-12 km (FL300-FL400). The stronger, more aviation-relevant jet. Shifts south in winter and north in summer. Dominant on North Atlantic and North Pacific eastbound routes.
Latitude 25-30°N (and S), altitude 10-16 km (FL330-FL500). Weaker and higher than the polar jet. Drives some Asia-North America eastbound routes and is significant for the Middle East-Europe and Middle East-Asia traffic streams.
Eastbound tailwind, westbound headwind
For an eastbound long-haul flight, the jet stream is free speed. New York to London with a 120 mph tailwind is up to 90 minutes shorter than the westbound trip. Westbound, the same jet is a headwind, so flight planners route slightly off the great-circle to avoid the strongest core.
On the North Atlantic the structure is formalized as the daily Organized Track System (NAT-OTS): eastbound tracks are published in the evening, optimized to ride the jet; westbound tracks in the morning, optimized to skirt it. Tracks shift hundreds of nautical miles north or south depending on the day's jet position.
Record-setting flights
On 18 February 2024, a Virgin Atlantic Boeing 787 reached a ground speed of 802 mph (1,290 km/h) over the Atlantic — pushed by an exceptionally strong jet stream of about 265 mph at FL350. The aircraft never exceeded its Mach limit in airspeed terms; the ground speed was simply true airspeed plus tailwind. Subsonic airliners regularly exceed 700 mph ground speed on eastbound North Atlantic crossings in winter.
Jet streams and clear-air turbulence
The strong wind shear at the edge of a jet stream — where wind speed changes rapidly with altitude or with latitude — is the classical source of clear-air turbulence. Forecast charts mark expected zones of significant CAT for flight planning. Pilots may climb above, descend below, or fly around the strongest shear to give passengers a smoother ride. See clear-air turbulence guide.
Seasonal and climatic shifts
Jet streams strengthen in winter (when the equator-to-pole temperature contrast is largest) and weaken in summer. They also shift latitude — polar jets dip south in winter, lifting north in summer. Several peer-reviewed studies have reported a strengthening of upper-level wind shear in recent decades, with implications for both turbulence frequency and route economics. The mechanism is debated; the trend itself is observed in radiosonde and reanalysis data.
How to see the jet stream
- →NOAA Aviation Weather Center publishes daily 200 hPa, 250 hPa, 300 hPa upper-wind charts
- →The World Area Forecast Centres (WAFC London, WAFC Washington) publish global jet stream forecasts for flight planning under ICAO Annex 3
- →Public-facing maps from windy.com, NOAA, Met Office show real-time jet stream cores and forecast tracks
Sources
- NOAA Jet Stream Education — noaa.gov/jetstream
- WMO Aerodrome Meteorological Observation and Forecast Study Group
- ICAO Annex 3 — Meteorological Service for International Air Navigation
- NAT OPS Bulletins — North Atlantic Organized Track System
- FAA Aeronautical Information Manual (AIM), Chapter 7 — Meteorology