# How to read a turbulence forecast without scaring yourself

> Turbulence forecasts are decent at where and weak at what you'll feel. What the numbers mean, how well they do, and how often to look.

By Derek Johnson. Updated Nov 7, 2026. Source: https://skycapapp.com/articles/ride/how-to-read-a-turbulence-forecast/

Read a turbulence forecast once, the night before, for one thing: does this flight look calmer, typical or bumpier than most? A forecast can say that with some skill. It can't say what your seat will feel at 7:42, and any map that looks as though it can is promising more than the science has.

## What the forecast is

The FAA's handbook describes the main US public forecast plainly. It runs more than 10 turbulence calculations on weather model data, checks each against recent reports from aircraft, and weights them by how well each is matching. It's issued hourly, hour by hour for three hours and then every three hours out to 18 hours, with no forecaster editing the result.

That description explains most of what the forecast can't do.

It stops at 18 hours. Anything you look at days ahead is coarser than this, or a guess.

It gets better with more aircraft reporting. The handbook says it improves in daylight and where traffic is heavy, so a red-eye over the ocean is its weakest case.

It doesn't specifically forecast bumps from convective clouds or small-scale terrain. Thunderstorms get their own forecasts, and in the NTSB's count convective turbulence was present in 64 of 111 airline accidents. A calm turbulence map tells you nothing about a shower on the climb.

## What the numbers and words mean

The number is eddy dissipation rate. It measures how stirred up the air is, and it's the international standard for automated turbulence reports. Because it describes the air and not the aircraft, the same value feels different in a regional jet and a 777. The public forecast is scaled to three aircraft weight classes for that reason. A consumer site quoting one number for "the route" is skipping that step.

The words are older, and they were written for pilots reporting to each other. They're descriptions of what happens in the cabin:

| Pilot's word | What the FAA says happens inside |
|---|---|
| "Light" | Slight strain against belts. Food service can continue, and walking is little or no trouble. |
| "Moderate" | Definite strain against belts. Loose objects move. Walking and food service are difficult. |
| "Severe" | Thrown hard against belts. Walking and food service are impossible. |

Notice what the middle row says. The handbook adds that in "moderate" the aircraft stays in positive control at all times. A word that sounds alarming on a map means the coffee stops.

## How good it is, tested

I checked forecast skill on the kind of forecast a flyer would actually see. Forecasts issued 3 hours before departure on 17 busy US routes were compared with 3,405 pilot reports from about a day and a half in early November 2026, all at 20,000 feet or higher.

Given one report of real bumps and one report of smooth air, the forecast ranked the bumpy one higher about three times in four. (The statistic is an AUC of 0.75, where 0.5 is a coin flip.) That's useful and well short of certain.

The test also showed how a label that looks exact can mislead. A rule that called a flight rough whenever any single point on the route crossed a line fired on 64% of flights, and on 72% of flights where pilots reported only smooth air. So I dropped it. Rating the whole flight against a typical one held up better: on the same 572 flights, 53% of those pilots found bumpy were rated bumpier and 14% calmer, while 26% of calm flights were rated bumpier.

Read that last figure the right way round. About one calm flight in four gets the word "bumpier", and some bumpy flights get "calmer". I also set that scale using these same flights, so a fresh test would likely come in lower, and a day and a half in November isn't a year.

That's why I think "calmer, typical, bumpier" is the honest scale. It claims about as much as the forecast knows.

## How to look at one

Two people who work with anxious flyers, Alex Gervash and Lawrie Jones, make the same case: checking again and again makes things worse. You get a moment of relief, and then the doubt comes back. A "smooth" forecast also sets you up for any bump to feel like a betrayal. Both have something to sell or a practice to run, and I think they're right anyway.

So look once. Note the shape: whether the bumps are forecast early, late or somewhere over the mountains. Then close it. Rechecking at the gate adds very little, because the crew has newer information than you do, including pilot reports from the flights ahead. They can ask for another altitude. You can't.

What a forecast can do for you is give the bumps a place in the flight. "About 20 minutes over the Rockies, then calm" is easier to sit through than a shake with no explanation. If you get a bump the forecast didn't mention, the forecast was wrong, and nothing else has changed.

Whatever it says, the part you control is the same: [the belt, the whole time you're seated](/articles/ride/is-turbulence-dangerous/). If you're flying a route with a reputation, [the most-turbulent lists](/articles/ride/most-turbulent-routes/) say less than they seem to. And for a stretch of forecast bumps at night, [the window](/articles/window/night-flights-what-you-can-see/) beats the seatback map.

> Skycap gives you one outlook the evening before, in words, and says so if it changes. [See how the ride forecast works](/app/features/#before)

## Sources

- [FAA Aviation Weather Handbook (FAA-H-8083-28A), chapters 19, 24 and 27](https://www.faa.gov/sites/faa.gov/files/FAA-H-8083-28A_FAA_Web.pdf)
- [NTSB, Preventing Turbulence-Related Injuries in Air Carrier Operations (NTSB/SS-21/01), 2021](https://www.ntsb.gov/safety/safety-studies/Documents/SS2101.pdf)
- [Alex Gervash, Turbulence forecasts before flight](https://alexpilotpsy.substack.com/p/turbulence-forecasts-before-flight)
- [Lawrie Jones, Fly Above Fear, on forecast apps](https://flyabovefear.com/help-desk/turbli/)