"Severe" solar storm alert issued, auroras expected farther south

Night sky watchers across the United States are in for another surprise tonight. A fresh blast of charged particles from the Sun – a G4 (Severe) geomagnetic storm – is currently sweeping past our planet, with colorful auroras expected as far south as Alabama.

The Sun, currently in a busy phase of its 11‑year cycle, has been hurling coronal mass ejections (CMEs) toward Earth at a brisk pace this week.

One of those eruptions has already sparked moderate geomagnetic storms and could strengthen after dusk on April 16, possibly drifting into April 18, setting the stage for a vivid show.

G4 (Severe) geomagnetic storm alert

The NOAA’s Space Weather Prediction Center (SWPC) has issued a G4 – or severe – geomagnetic storm conditions were observed at 5:25 PM Eastern Daylight Time on April 16, 2025, with the updated alert stretching into April 17-18, 2025.

A coronal mass ejection, or CME, has bombarded Earth with solar particles throughout the day, and forecasters are still deciding whether the heightened solar wind comes from a second burst or a single, combined front.

Geomagnetic activity can climb quickly when the CME’s magnetic field points south, opposite Earth’s field, but if it aims north, the response is usually mild.

“The strength of the light show will depend on how Earth’s magnetic field interacts with the solar bursts,” said Shawn Dahl at the SWPC.

Because the current CME pushed solar wind speeds to roughly 375 miles per second – up from about 250 miles per second earlier this week – experts consider conditions ripe for vigorous auroras if the magnetic orientation tilts the right way.

How geomagnetic storms impact Earth

During strong events the area of greatest impact sits poleward of about 50 degrees geomagnetic latitude, but mid‑latitude regions can feel the ripple.

Power companies may notice voltage swings and an uptick in false alarms from protective equipment.

Satellites in low Earth orbit can encounter extra drag; their instruments may experience surface charging; and attitude‑control systems sometimes struggle until the storm passes.

Navigation signals can wander, leading to intermittent GPS loss‑of‑lock and bigger range errors, while high‑frequency radio reception may fade in and out.

Severe storms are even capable of scrambling radio and GPS communications altogether, a reminder of why operators pay attention.

History offers cautionary tales: in 1859, a violent outburst lit Hawaiian skies and set telegraph lines ablaze, and in 1972 another storm is thought to have detonated magnetic U.S. sea mines off Vietnam.

Geomagnetic storm, auroras, and the South

Thanks to Geomagnetic K-index of 8 (G4) alert issued minutes ago, auroras may be seen tonight as far south as Alabama and northern California.

Clear, dark skies away from city glare remain the key.

NASA’s Kelly Korreck suggests heading to a local or national park and snapping a quick photo with a smartphone because the sensor can reveal faint colors invisible to the eye.

“Enjoy it,” said Korreck. “It’s this great show … from the sun to you.”

End of this 11-year solar cycle

Every 11 years, the Sun’s magnetic poles trade places, twisting the star’s field lines and fueling flares and CMEs. The current surge is expected to last at least through the end of 2025, though scientists will not pinpoint the precise peak until months afterward, according to NASA and NOAA.

That sustained activity explains why colorful auroras have already reached Germany, the United Kingdom, New England, and New York City.

Last spring brought the strongest geomagnetic storm in two decades, and skygazers can expect more sporadic shows as the cycle rolls on.

While no one can forecast these storms months ahead, the Space Weather Prediction Center issues watches in the days before impact so utilities, satellite operators, and curious night owls can prepare.

Digging into the data

Solar activity over the past 24 hours has been moderate. Region 4055 unleashed an M1.3 flare at 2:13 p.m. Eastern Daylight Time on April 15 and a smaller C8.1 flare at 12:39 a.m. on April 16 before rotating out of direct view.

With its departure, the chance of additional M‑class flares has slipped from about 75 percent to 50 percent through April 18, while the odds of the more powerful X‑class events remain low.

GOES‑19 registered electrons above 2 million electron volts, peaking at 2,380 particles per square centimeter per second per steradian around 12:20 p.m. on April 15; proton levels have stayed quiet.

A shockwave from a CME that left the Sun on April 13 arrived near Earth at 12:37 p.m. Eastern on April 15.

Magnetometer readings spiked to 28 nanoteslas just after 2:20 p.m. and later eased to between 12 and 18 nanoteslas.

The crucial north–south component, known as Bz, dipped to –20 nanoteslas, a value capable of stirring strong geomagnetic activity.

These effects are expected to linger into early April 17 before weakening, though a coronal hole is likely to keep the solar wind elevated into April 18.

As a result, G2 storms flared on the evening of April 15; G1 to G2 levels are likely throughout April 16, with a chance for G3 periods; and minor disturbances could persist on April 17 before conditions gradually settle.

What happens next?

With Region 4055 gone, the spotlight now shifts to Region 4060, which has shown only mild growth, and to freshly arriving Region 4062, whose magnetic structure remains unclear.

Unless one of those areas unexpectedly flares, electron levels should hover in the normal to moderate range and proton counts should stay quiet.

Forecast models suggest the current storm will weaken late on April 17, but magnetospheric conditions may stay unsettled until the high‑speed stream from the coronal hole passes sometime on April 18.

Keep an eye on the Space Weather Prediction Center’s aurora map or your favorite alert app; step outside if skies cooperate; and you just might catch nature’s neon headline.

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