How strong was the May 2024 Gannon storm?

It reached G5 (extreme) on NOAA's scale — the first G5 since November 2003 — with the Dst index bottoming near −412 nT, the strongest geomagnetic storm in over two decades.

Where was the aurora visible during the Gannon storm?

Naked-eye aurora was reported from 24.3° magnetic latitude in the north (Hanle, India) and −23.2° in the south (Tivoli, Namibia). Cameras caught red glow from even lower latitudes, including Mexico and the Caribbean.

Why is it called the Gannon storm?

It was named in memory of space physicist Jennifer Gannon, who died shortly before the storm. The name was adopted widely across the space-weather community.

Can I see what the Gannon storm looked like from my town?

Yes — the observatory's 3D reconstruction lets you stand at any point on Earth and watch the storm's whole night pass overhead, in camera colors or an honest naked-eye rendering.

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THE GANNON STORM · MAY 2024

On the night of May 10–11, 2024, the strongest geomagnetic storm in over two decades pushed the aurora to latitudes most people alive had never seen it from. This page is the record; the reconstruction is the replay — built from satellite measurements and validated against 486 star-calibrated photographs. This storm is why the observatory exists.

▶ Replay this storm in 3D. A measured reconstruction from DMSP/SSUSI, POES and AMPERE data — the scene opens mid-substorm-expansion on the night of May 10–11. Scrub the timeline, or stand under it from any town on Earth.

explore it in the observatory →stand under it: Nova Scotia →aurora australis: Tasmania →

What happened

Active region 13664 grew into one of the most flare-productive regions of Solar Cycle 25 and launched a train of coronal mass ejections at Earth. They arrived stacked on May 10, and the magnetosphere answered with the first G5-level storm since the Halloween storms of 2003¹. The Dst index bottomed near −412 nT¹ — the deepest since 2003 — and NOAA's G-scale pinned at its ceiling⁵.

The storm was named for space physicist Jennifer Gannon, who had died suddenly days before. The name stuck across the community — a working scientist's name on the storm that brought her science to half the planet's night sky.

How far south (and north) it reached

Citizen-science reports collected during the storm put naked-eye aurora at 24.3° magnetic latitude in the northern hemisphere (Hanle, India) and −23.2° in the south (Tivoli, Namibia)² — deep into the subtropics in both hemispheres. Red SAR-arc and stable red glow were photographed from Mexico and the Caribbean; the classic curtained oval stood over the northern United States, central Europe, New Zealand and Tasmania.

Why this reconstruction is different

The observatory's Gannon scene is not an artist's impression. The auroral oval's position, brightness and structure are fit frame-by-frame from DMSP/SSUSI ultraviolet imagery, POES particle precipitation and AMPERE magnetic-field data, then validated against 486 star-calibrated photographs submitted during the storm — each photo's star field solved so the aurora's true border latitude could be measured against the model⁴. Both hemispheres are fit — the aurora australis over Australia and New Zealand is reconstructed from the same satellite boundary data, with VIIRS nighttime imagery draped where the satellites actually saw it.

Frequently asked questions

How strong was the May 2024 Gannon storm?: It reached G5 (extreme) on NOAA’s scale — the first G5 since November 2003 — with the Dst index bottoming near −412 nT¹, the strongest storm in over two decades.
Where was the aurora visible during the Gannon storm?: Naked-eye aurora was reported from 24.3° magnetic latitude in the north (Hanle, India) and −23.2° in the south (Tivoli, Namibia)². Cameras caught it from even lower latitudes — Mexico, the Caribbean, and across the southern-hemisphere subtropics.
Why is it called the Gannon storm?: It was named in memory of space physicist Jennifer Gannon, who died shortly before the storm. The name was adopted widely across the space-weather community.
Can I see what the Gannon storm looked like from my town?: Yes — the 3D reconstruction lets you stand at any point on Earth and watch the storm’s whole night pass overhead, in camera colors or honest naked-eye rendering.

Sources

Numbered references for the claims above.

Hayakawa, H. et al. (2025). The solar and geomagnetic storms in 2024 May: a flash data report. Astrophys. J. 979, 49. doi:10.3847/1538-4357/ad9335
Grandin, M. et al. (2024). The Gannon Storm: citizen science observations during the geomagnetic superstorm of 10 May 2024. Geoscience Communication 7, 297–316. doi:10.5194/gc-7-297-2024
World Data Center for Geomagnetism, Kyoto — final/provisional Dst index. wdc.kugi.kyoto-u.ac.jp
The Observatory’s own reconstruction pipeline and validation gates are documented on data & methods.
NOAA Space Weather Prediction Center — NOAA Space Weather Scales (G-scale). swpc.noaa.gov

More storms: October 2024 · November 2025 · Halloween 2003 · Carrington 1859 · St Patrick's 2015

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By The Space Weather Observatory · checked against the data & methods record · Updated August 21, 2026

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