# Turbulence forecast for your flight: how it works and how to read it

**Short answer:** A turbulence forecast estimates where along your route, and when, the air is likely to be bumpy. It combines a weather model's winds with turbulence formulas, official warnings (SIGMETs) and recent pilot reports. Check it a day or so ahead and again before you leave. It shows a likelihood, not a promise: turbulence is small and fast-changing, so keep your seat belt on when seated.

## Key facts
- NOAA's Global Forecast System (GFS) weather model runs 4 times a day and forecasts up to 16 days ahead [1].
- GFS data is open to the public and free to use [2].
- Its grid points are about 18 miles (28 km) apart, many times larger than the eddies that bump an airplane, so forecasters compute turbulence indexes from its winds [1][3].
- The US Graphical Turbulence Guidance (GTG) forecasts up to 18 hours ahead, and its nowcast updates every 15 minutes [4].
- A SIGMET warns of severe or extreme turbulence and is valid for up to 4 hours; an AIRMET covers moderate turbulence [5].
- From 2009 to 2018, storm-related (convective) turbulence was present in 57.7% of US airline turbulence accidents and clear-air turbulence in 28.8% [5].

## What is a turbulence forecast?
A turbulence forecast is a prediction of where rough air is likely, at which altitudes and at what times, computed from weather-model data and real observations. A route turbulence forecast narrows that down to one flight: it follows the path and altitude your airplane will fly, minute by minute, and tells you where light or moderate bumps are more likely.

It's the same idea as a rain forecast. "70% chance of rain" doesn't promise rain at your door; it describes the odds over an area. Turbulence forecasts work the same way, at a much smaller scale.

## Where turbulence forecasts get their data
Every turbulence forecast, from the ones airline dispatchers use to the ones in apps, is built from some mix of four ingredients.

### 1. A weather model's winds
Weather models such as NOAA's GFS simulate the atmosphere on a three-dimensional grid. GFS runs four times a day, at 00, 06, 12 and 18 UTC, with grid points about 18 miles apart [1]. That includes the winds at cruising altitude: the 200 hPa pressure level, for example, is roughly 39,000 feet [3].

### 2. Turbulence indexes
The eddies that shake an airplane are far smaller than a model's grid, so models can't show them directly [3]. Instead, forecasters calculate indexes from the model's winds and temperatures that flag where turbulence is likely [3]. Most look for strong wind shear: wind that changes speed or direction sharply with height or across distance.

One classic clear-air turbulence index was developed in the early 1990s and, by 2010, was in use at many aviation forecasting facilities worldwide [6]. It combines vertical wind shear with how strongly the flow is being stretched. Modern products like GTG blend many indexes into one forecast [3][7]. To understand what these indexes are looking for, see [what causes turbulence](/guides/what-causes-turbulence).

### 3. Official warnings
Weather offices issue advisories when hazardous weather is present or expected [5]:

- **SIGMET:** widespread weather that's potentially hazardous to all aircraft, including severe or extreme turbulence; valid for up to 4 hours.
- **AIRMET:** weather that doesn't meet SIGMET criteria but still matters, such as moderate turbulence.

### 4. Pilot reports
A pilot report (PIREP) is a pilot's own description of the weather they met: where, at what altitude, and how bumpy. Reports are real observations, but they aren't quantitative, and they're patchy in space and time [3]. Public reports come mainly from the US and the North Atlantic [8]. Learn to read them in [PIREPs and SIGMETs explained](/guides/pilot-reports-and-sigmets).

## How far ahead can turbulence be forecast?
Like any weather forecast, a turbulence forecast gets sharper as departure gets closer. Here's what's available at each stage:

| When | What you can check | How to use it |
|---|---|---|
| 1 to 3 days before | Model-based forecasts of jet-stream winds and shear along your route | Get a feel for the overall pattern; don't fix on details |
| The day before | A fresher model run, often with smaller changes | Note where along the route bumps are more likely |
| A few hours before | Current SIGMETs and AIRMETs, the latest pilot reports, short-range guidance like GTG (out to 18 hours) [4][5] | Your best picture before boarding |
| In flight | Your crew's radar, reports from other aircraft and their airline's tools | Follow the seat belt sign and your crew |

Weather models themselves run out to 16 days [1], but turbulence depends on small, fast-changing details, so longer-range turbulence outlooks deserve a big pinch of salt.

## How to read a turbulence forecast
1. **Look at the level.** Most forecasts use smooth, light and moderate. Light means a slight strain against your belt and walking is easy; moderate means walking and service are difficult [5]. See [turbulence levels explained](/guides/turbulence-levels).
2. **Look at when, not just whether.** "Light for 20 minutes about two hours in" is far more useful than "bumpy." Plan your restroom visit and hot drink for the smooth stretches, and see [the best time to fly for less turbulence](/guides/best-time-to-fly-for-less-turbulence) if you're still choosing a flight.
3. **Check the cause.** Storm areas move and pilots route around them. Jet-stream bumps tend to sit in bands that crews can sometimes climb or descend out of. Routes over big mountain ranges have their own pattern; see [the most turbulent flight routes](/guides/most-turbulent-routes).
4. **Treat "severe" with care.** Severe turbulence is rare and is normally flagged by an official SIGMET. When one is on or near your route, it's there so the people planning your flight can avoid it.
5. **Re-check closer to departure.** Forecasts are updated several times a day. For a five-minute, step-by-step check of your own flight, see [will there be turbulence on my flight today?](/guides/will-my-flight-be-bumpy)
6. **Remember it's a likelihood.** A smooth forecast doesn't promise a smooth ride, and a bumpy one often turns out milder.

## What a turbulence forecast can't tell you
- **The exact bump.** Forecasts describe areas and chances, not the moment you'll feel a jolt.
- **Every storm.** New thunderstorms can pop up between model runs. In the US, convective turbulence guidance exists, but GTG's storm-related layer covers only the lower 48 states [4].
- **What the airline knows.** Many professional turbulence products are proprietary, and airlines share their own turbulence observations mostly within their own staff [5].
- **Whether you'll be surprised.** Even professionals can't catch everything. In the NTSB's study, flight crews were aware of a turbulence risk before 53.2% of turbulence accidents [5]. That's why the seat belt matters more than any forecast.

## Do airlines use turbulence forecasts?
Yes, every day. Dispatchers and pilots use official products like SIGMETs, AIRMETs and GTG, plus their own airline's tools [5]. Worldwide aviation forecasts (WAFS), produced in London and Washington, use the same GTG method for their global turbulence data [7]. Pilots then adjust in the air, changing altitude or route when reports or their radar suggest smoother air nearby.

## How Sorapuff helps
Sorapuff's route turbulence forecast does this for your flight. From your airports and departure time, it downloads NOAA's GFS winds along your route, computes a well-known clear-air turbulence index on your phone, and adds SIGMETs and recent pilot reports from aviationweather.gov. You get a minute-by-minute timeline of smooth, light or moderate; "severe" only comes from an official SIGMET. It's checked against thousands of real pilot reports. One forecast is free; Pro adds unlimited forecasts up to 3 days ahead ([pricing](/pricing)).

## FAQ
### How accurate are turbulence forecasts?
They're useful but imperfect. Forecasts can reliably show areas where turbulence is more or less likely, but not the exact moment or the exact bump, because the eddies involved are far smaller than any weather model's grid. Treat a forecast as a likelihood: helpful for planning, never a promise. Your crew has real-time radar and reports on top of it. We published how our own forecast scored against 3,083 pilot reports in [how accurate turbulence forecasts are](/guides/how-accurate-are-turbulence-forecasts).

### How far in advance can I check turbulence for my flight?
You can look at model-based outlooks up to a few days ahead, and they get more useful as departure approaches. Official short-range guidance such as GTG looks up to 18 hours ahead, and SIGMETs and pilot reports describe the next few hours. Check once a day or two ahead, then again before you leave.

### Will my flight be bumpy?
A route forecast can tell you whether bumps are more or less likely, roughly where, and for how long. Many flights have a few minutes of light turbulence, which is normal and harmless for a belted passenger. If moderate bumps are forecast, plan to stay seated with your belt on during that stretch and follow your crew.

### Can I see the turbulence forecast pilots use?
Partly. The Aviation Weather Center publishes US turbulence guidance (GTG), SIGMETs, AIRMETs and pilot reports for free at aviationweather.gov, aimed at pilots. Airlines add their own proprietary tools and data. Apps translate public data into a forecast for your specific route and time.

### What does a SIGMET on my route mean?
It means forecasters expect hazardous weather, such as severe turbulence or storms, in an area for up to 4 hours. It's a planning tool for airlines and pilots, who route around the area or choose another altitude. It doesn't mean your flight will fly through it. Keep your belt fastened and follow your crew.

## Sources
1. [Global Forecast System (GFS), NOAA National Centers for Environmental Information](https://www.ncei.noaa.gov/products/weather-climate-models/global-forecast)
2. [NOAA Global Forecast System (GFS), Registry of Open Data on AWS](https://registry.opendata.aws/noaa-gfs-bdp-pds/)
3. [Evidence for Large Increases in Clear-Air Turbulence Over the Past Four Decades, Geophysical Research Letters (2023)](https://doi.org/10.1029/2023GL103814)
4. [Graphical Forecasts for Aviation help: Turbulence, Aviation Weather Center (NOAA)](https://aviationweather.gov/gfa/help/?page=turb)
5. [Preventing Turbulence-Related Injuries in Air Carrier Operations Conducted Under Title 14 CFR Part 121, Safety Research Report SS-21/01 (2021), NTSB](https://www.ntsb.gov/safety/safety-studies/Documents/SS2101.pdf)
6. [Improvements to an Operational Clear-Air Turbulence Diagnostic Index, 90th AMS Annual Meeting (2010), American Meteorological Society](https://ams.confex.com/ams/90annual/webprogram/Paper162948.html)
7. [New 0.25 degree WAFS Hazard Data, training material (November 2020), ICAO](https://www.icao.int/sites/default/files/METP/Documents/Nov-2020-New-WAFS-Hazard-data-training-material.pdf)
8. [Data API, Aviation Weather Center](https://aviationweather.gov/data/api/)

Updated November 13, 2026 · https://sorapuff.app/guides/turbulence-forecast

## Related guides

- [Will There Be Turbulence on My Flight Today? How to Check](https://sorapuff.app/guides/will-my-flight-be-bumpy): Will there be turbulence on your flight today? Check it in 5 minutes with free official maps, warnings and pilot reports, and know what they can't tell you.
- [How Accurate Are Turbulence Forecasts? We Checked Ours](https://sorapuff.app/guides/how-accurate-are-turbulence-forecasts): How accurate are turbulence forecasts? How they're scored against pilot reports, what NOAA's checks found, and our own test on 3,083 US pilot reports.
- [What Causes Turbulence? Clear Air, Storms and More](https://sorapuff.app/guides/what-causes-turbulence): Turbulence comes from uneven air: wind shear near the jet stream, storms, mountains and aircraft wakes. Here's each cause and how pilots handle it.
- [What Is a PIREP? What Is a SIGMET? Explained Simply](https://sorapuff.app/guides/pilot-reports-and-sigmets): A PIREP is a pilot's report of the weather met in flight; a SIGMET is an official hazard warning. Learn to read both and what they mean for your flight.