The Hurricane Cone is Changing in 2026: What the New "90% Ellipse" Means for Your Community
Hurricane season is almost back, and this year, the map you have always relied on just got a major upgrade.
If you live in a storm-prone area, you are intimately familiar with the “cone of uncertainty.” It is that expanding, funnel-like shape showing where a hurricane might travel. The wider the cone gets, the further into the future meteorologists are looking. Historically, it has been the National Hurricane Center’s (NHC) best guess at where the center of the storm will go.
But starting in 2026, the NHC is introducing an experimental update to that map. Here is exactly what is changing, why it matters, and what it means for your local flood defense strategy.
The Problem with the Old Cone (The 67% Circle)
Since 2007, the standard NHC cone has been built by enclosing the area swept out by expanding circles anchored at each forecast point. Those circles were sized to the 67th percentile of NHC track errors over the previous five years. It was the best tool available at the time, but it had two meaningful limitations.
- The 67% Rule: The circular cone was only designed to capture the storm center’s actual path about 67% of the time. That meant roughly one out of every three storms wandered completely outside the lines.
- Uniform Errors: Circles treat every type of forecasting error the same way. But storms do not make perfectly circular mistakes. A storm can run ahead of schedule, fall behind, or drift sideways, and those are three very different problems that a single circle cannot distinguish between.
1 in 3 storms escaped the cone entirely
9 in 10 storm centers stay within the cone
Meet the 2026 Experimental Cone (The 90% Ellipse)
To fix this, the NHC is rolling out an experimental cone that replaces circles with ellipses (oval shapes).
Why is an oval better than a circle? Because it separately accounts for two distinct kinds of forecast error:
- Along-track error (speed): Did the storm move faster or slower than predicted?
- Cross-track error (direction): Did the storm drift further left or right than predicted?
The NHC calculates each of these independently and sizes the ellipse axes to the 90th percentile of those errors from the previous five years. Ellipses are anchored at each forecast point: 12, 24, 36, 48, 60, 72, 96, and 120 hours out. The cone is formed by smoothly connecting the area swept out by all of them.
The result is a cone that stretches and narrows based on the actual shape of forecast uncertainty rather than a one-size-fits-all circle. And because it is built to the 90th percentile instead of the 67th, the storm center is expected to stay inside it nine times out of ten.
Data Visualization: ESR
Data Source: NHC / NOAA
What It Looks Like on Real Storms
The NHC will display the experimental cone alongside the operational cone during the entire 2026 season. The comparison graphics below use real historical storms to show exactly what that looks like. In each image, the red dashed line outlines the old 67% circle cone, and the white shaded area shows the new 90% ellipse cone.
Pacific — Hurricane Lane, August 2018. Red dashed: old 67% circle cone. White shaded: new 90% ellipse cone.
Atlantic — Hurricane Milton, October 2024. Red dashed: old 67% circle cone. White shaded: new 90% ellipse cone.
In both cases, the ellipse cone produces a noticeably different shape. Depending on a storm’s behavior, it may be narrower in one direction and wider in another, which is a more honest representation of where the danger actually lies.
What the New Cone Looks Like on Its Own
This is what you will see on hurricanes.gov when the NHC issues its experimental cone during the 2026 season. No overlay, no comparison. Just the new 90% ellipse cone as a standalone graphic.
Pacific — The new 90% ellipse cone. Hurricane Lane, Eastern Pacific, August 2018.
Atlantic — The new 90% ellipse cone. Hurricane Milton, Atlantic, October 2024.
What This Means for Your Storm Prep
This new shape is significantly more realistic. If your city falls inside the new 90% cone, take it seriously.
Have Your Say
The NHC will display the experimental cone alongside the operational cone during the entire 2026 season so the public can directly compare them. The NHC is actively seeking public feedback on this new tool through November 30, 2026.
You can view the interactive maps, read the full methodology, and submit your feedback directly at the official NHC Experimental Cone page.
Don’t wait for the cone to reach your city
At Emergency Sandbag Response (ESR), we help municipalities replace chaotic, last-minute sandbag lines with automated, high-speed flood defense logistics. Schedule a meeting with our team today.
📅 Schedule a MeetingOr reach us directly