Why the National Hurricane Center’s “Cone of Uncertainty” Is Changing

Every hurricane season, one graphic ends up everywhere: on TV, in social posts, and in emergency briefings. Most people call it the “cone of uncertainty.” The National Hurricane Center’s official name for it is the track forecast cone, and it is meant to show the probable path of the storm’s center over time, not the full area where impacts will happen. That distinction matters because dangerous wind, rain, storm surge, tornadoes, and flooding can all happen well outside the cone.

How the Cone Is Built

The cone isn’t based on a single forecast or a meteorologist’s best guess in the moment. It’s grounded in historical data.

Each year, the NHC reviews forecast errors from the previous five years to determine how wide the cone should be. The goal is to capture where the storm’s center has historically ended up relative to past forecasts.

More specifically, the cone is designed so that the storm’s center stays within it about two-thirds of the time (roughly 67%). That means it’s a probability tool—not a guarantee.

Why the Cone Changes Size Each Year

You may have noticed that the cone sometimes looks bigger or smaller from one year to the next. That’s not a redesign—it’s part of how the system works.

Because the cone is based on recent forecast performance:

• If forecasts improve, the cone tends to shrink

• If forecasts become less accurate, the cone can expand

For the 2026 Atlantic season, for example, the cone ranges from about 25 nautical miles at 12 hours to 200 nautical miles at 120 hours. Those numbers reflect how accurate forecasts were from 2021 to 2025.

So while the cone does change size, that annual adjustment is a long-standing feature—not a new experiment.

What’s New: The Experimental Cone

The real update in 2026 is the introduction of an experimental cone graphic, which will be released alongside the standard version.

At first glance, it may look different—and that’s intentional.

Instead of using circles, the experimental cone uses ellipses. This allows it to better reflect how forecast errors actually behave, which are not evenly distributed in all directions.

A Better Way to Represent Uncertainty

One of the main reasons for this change is that storm forecasts tend to have two different kinds of error:

• Along-track error – whether the storm moves faster or slower than expected

• Cross-track error – whether the storm shifts left or right of the forecast path

  
  

The traditional cone treats uncertainty as evenly spread in all directions. The experimental version does not. By using ellipses, it can show when uncertainty is stretched more in one direction than another.

This is a more realistic representation of how storms actually deviate from forecasts.

Why the Experimental Cone May Look Bigger

Another noticeable difference is that the experimental cone is often larger. That’s not because the forecast is worse—it’s because the method is different.

The current cone is based on capturing about 67% of past forecast errors. The experimental version expands that to 90%.

In practical terms, that means the experimental cone is designed to include a much wider range of plausible outcomes. It’s not exaggerating risk—it’s showing more of the uncertainty that already exists.

The Communication Problem NHC Is Trying to Solve

For years, one of the biggest challenges hasn’t been forecasting storms—it’s helping people interpret the forecast correctly.

Some of the most common misunderstandings include:

• Assuming impacts only occur inside the cone

• Believing areas outside the cone are “safe”

• Underestimating risk in inland areas

The experimental cone is part of a broader effort to address these issues. By better visualizing uncertainty, the NHC hopes people will make more informed decisions, even if they’re not directly in the forecast path.

Another 2026 Update: Inland Warnings

Alongside the experimental cone, there’s another important change to how the cone graphic is presented.

Starting in 2026, the operational cone will also display:

• Inland tropical storm watches and warnings

• Inland hurricane watches and warnings

This change reflects a growing emphasis on inland impacts. Hurricanes don’t stop at the coastline, and including these warnings directly on the map helps reinforce that reality.

Important: This Is Still Experimental

It’s worth emphasizing that the new cone is still being tested.

The NHC will:

• Release it alongside the current cone during the 2026 season

• Collect feedback through November 30, 2026

The traditional cone is not going away for now. Any long-term changes will depend on how well the experimental version performs and how useful it is to the public.

The Bottom Line

The cone isn’t being overhauled—it’s being refined.

The current version already evolves each year based on forecast accuracy. The experimental version takes that a step further by better representing how storms can deviate from their predicted path.

At its core, this isn’t just about meteorology. It’s about communication. The goal is to help people better understand risk—and ultimately make safer decisions when it matters most.

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Sources: iii.org, nhc.noaa.gov