Strong Geomagnetic Storm Possible Tuesday — What It Means for Satellites, GPS and Aurora Watchers

Federal space weather forecasters warn a large solar eruption may reach Earth early to midday Tuesday, raising the possibility of a strong geomagnetic storm and widespread auroras.

What NOAA says: The National Oceanic and Atmospheric Administration's Space Weather Prediction Center (SWPC) reports a coronal mass ejection (CME) tied to an M8.1 solar flare is on a trajectory toward Earth. Forecasters say the CME could spark elevated geomagnetic activity and has the potential to produce a G3 (strong) event on the NOAA Space Weather Scale.

What a G3 Storm Means

A G3 classification is considered "strong" and can cause limited but meaningful impacts to technology. Possible effects include temporary satellite service interruptions, degraded high-frequency (HF) radio communications, and reduced GPS accuracy. Strong storms also tend to produce vivid auroras visible much farther from the poles than usual.

Where Auroras May Appear

NOAA says the northern lights could be visible farther south than normal across large portions of the northern United States and in some states stretching from the lower Midwest to Oregon. Observers in those regions should watch the skies after local nightfall if conditions clear.

What Space Weather Is — And Why It Matters

Space weather refers to changing conditions in the space environment driven by the Sun, including streams of charged particles, plasma eruptions and bursts of radiation. Earth's magnetic field and atmosphere block many hazardous effects, but strong solar events can still disturb the magnetosphere and upper atmosphere — producing auroras and disrupting technologies that rely on satellites, radio links and precise timing.

How Scientists Monitor and Measure It

Both NASA and NOAA continually monitor solar activity, but NOAA's SWPC specializes in forecasting events that could affect Earth and critical infrastructure. SWPC uses the NOAA Space Weather Scales to communicate severity for geomagnetic storms (G1–G5), solar radiation storms and radio blackouts. The geomagnetic G-scale is tied to the planetary K-index (Kp), which measures short-term fluctuations in Earth's magnetic field on a 0–9 scale.

Recent Notable Events

In May 2024 a G5 storm — the strongest in more than 20 years — produced spectacular global auroras and coincided with real-world impacts such as tripped high-voltage lines, overheating transformers and GPS-guided agricultural equipment veering off course. In late October 2003, a cluster of intense solar storms disrupted power grids and aviation systems and produced auroras as far south as Texas and Florida. More recently, an R3 (strong) radio‑blackout event impacted Australia and parts of Southeast Asia, temporarily blocking HF radio communications on the sunlit side of Earth.

What You Should Do

For most people, the biggest opportunity is an unusually good aurora show. For operators of satellites, aviation, maritime and critical infrastructure, agencies recommend monitoring SWPC and NASA updates, following operational guidance, and preparing for possible short-term communications or navigation degradation. SWPC will issue watches and warnings with updated timing, intensity and impact guidance as the CME approaches.

Reporting and monitoring by NOAA and NASA; ABC News' Julia Jacobo contributed to earlier coverage.