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Solar Cycle 25: When the Sun Throws Punches

Solar Cycle 25: When the Sun Throws Punches

How a hyperactive solar cycle is stress-testing Earth's infrastructure and forecasting models

Overview

The sun unleashed its biggest punch in 23 years on January 19, 2026. An X1.9 solar flare from sunspot region AR4341 launched a coronal mass ejection that reached Earth in just 25 hours—nearly half the predicted travel time—triggering G4 severe geomagnetic storms, the strongest S4 radiation storm since the 2003 Halloween events, and aurora visible from Alabama to New Mexico.

Solar Cycle 25, which peaked in October 2024, has consistently defied forecasters who expected a quiet cycle. Instead, it produced over 50 X-class flares in 2024 alone and multiple G4/G5 storms. The January 2026 event underscores a critical gap: models predicted 40+ hours for CME arrival, but it took 25. As grid operators, satellite operators, and airlines adapt to faster-than-expected space weather, the declining phase of this cycle still holds the potential for extreme events through 2027.

Key Indicators

25 hrs
CME Transit Time
Traveled at ~1,700 km/s, arriving nearly half the predicted 40+ hours
G4/S4
Storm Severity
Strongest geomagnetic storm since 2003; first S4 radiation storm in 23 years
161
Peak Sunspot Number
Solar Cycle 25's smoothed sunspot number at October 2024 peak—40% above predictions
±12 hrs
CME Prediction Uncertainty
Average error margin in current space weather forecasting models

People Involved

SD
Shawn Dahl
NOAA SWPC Service Coordinator and Space Weather Forecaster (Active forecaster coordinating January 2026 storm response)

Organizations Involved

NO
NOAA Space Weather Prediction Center
Federal Agency
Status: Primary U.S. space weather forecaster issuing alerts and watches

The U.S. government's official source for space weather forecasts, alerts, watches, and warnings.

North American Electric Reliability Corporation
North American Electric Reliability Corporation
Regulatory Authority
Status: Enforces grid protection standards for geomagnetic disturbances

Develops and enforces reliability standards for North American power grids, including GMD protections.

Timeline

  1. G4 Conditions Continue; Aurora Reaches Southern U.S.

    Ongoing Impact

    Storm persists through January 20 UTC-day. Northern lights photographed from Alabama, Kentucky, and New Mexico. Power grids report manageable impacts.

  2. CME Arrives Early—G4 Storm Begins

    Major Storm

    CME traveling ~1,700 km/s reaches Earth in 25 hours instead of predicted 40+. G4 severe conditions reached within minutes.

  3. S4 Radiation Storm Declared

    Radiation Event

    NOAA declares the first S4 severe solar radiation storm since the 2003 Halloween storms. ISS crew shelters in shielded areas.

  4. X1.9 Flare Erupts from AR4341

    Solar Flare

    First X-class flare of 2026 triggers R3-strong radio blackouts across the Americas, Europe, and Africa. Full-halo CME detected.

  5. X5.16 Flare Triggers G4 Storm

    Major Storm

    Region AR4274 produces an X5.16 flare with a 1,950 km/s CME, causing the third-strongest geomagnetic storm of Cycle 25.

  6. NASA/NOAA Declare Solar Maximum

    Cycle Event

    Official announcement that Solar Cycle 25 reached maximum with a smoothed sunspot number of 161—exceeding the predicted peak of 115.

  7. X9.0 Flare—Strongest of Cycle 25

    Solar Flare

    Sunspot region AR3842 produces an X9.0 flare, the most powerful Earth-facing flare of the current cycle.

  8. First G5 Extreme Storm Since 2003

    Major Storm

    Multiple CMEs from sunspot region 3664 trigger the first G5 storm in 21 years. Aurora visible from Texas to Florida. 40 Starlink satellites lost.

  9. Starlink Loses 38 Satellites to Minor Storm

    Infrastructure Impact

    A G1 geomagnetic storm increases atmospheric drag, causing 38 of 49 newly launched Starlink satellites to reenter and burn up.

  10. Solar Cycle 25 Begins

    Cycle Event

    Solar minimum marks the start of Cycle 25, with a smoothed sunspot number of 1.8.

Scenarios

1

G5 Extreme Storm Strikes Before Cycle 25 Ends

Discussed by: Space.com, NOAA forecasters, and solar physics researchers

Studies predict 2±1 extremely strong flares (>X14) may occur between May 2026 and December 2027 as Cycle 25 declines. A direct-hit CME from such an event could produce G5 conditions with more severe infrastructure impacts than May 2024. NOAA's Shawn Dahl noted the January 2026 storm had potential to escalate to G5. The declining phase of solar cycles has historically produced some of the strongest individual events.

2

Major Satellite Constellation Loss During Storm

Discussed by: MIT Technology Review, space weather researchers, satellite operators

The February 2022 Starlink loss demonstrated that even minor G1 storms can destroy satellites at vulnerable orbital insertion altitudes. A G4 or G5 storm during a large satellite deployment could cause significant losses. Operators have since adjusted procedures, but the risk of thermospheric density spikes catching newly launched constellations remains a concern as megaconstellation deployments continue.

3

Forecasting Models Improve to Sub-6-Hour Accuracy

Discussed by: Nature Scientific Reports, arXiv space weather research, NOAA

Recent AI models have shown unprecedented accuracy in predicting CME arrivals, with some achieving uncertainty as small as one minute in test cases. NOAA's Space Weather Follow On-L1 satellite, launched in 2025, adds coronagraph capabilities for earlier CME detection. If operational forecasting adopts these improvements, the gap between prediction and reality could narrow substantially, giving grid operators and airlines more reliable lead time.

4

Regional Power Grid Disruption During Severe Storm

Discussed by: NERC, USGS, Lloyd's of London, power grid analysts

The January 2026 storm produced manageable grid impacts, but NERC standards are designed for 1-in-100-year events, not Carrington-scale storms. USGS modeling shows the U.S. Midwest and East Coast are most vulnerable due to underlying geology. A sustained, well-directed G5 storm could overwhelm protective systems. Transformer replacement backlogs of up to two years add to long-term risk.

Historical Context

Quebec Blackout (1989)

March 1989

What Happened

On March 13, 1989, a severe geomagnetic storm caused Hydro-Québec's power grid to collapse in under 90 seconds. Telluric currents overwhelmed seven static var compensators in sequence, causing the entire La Grande network to separate. Six million people lost power for nine hours.

Outcome

Short Term

Quebec spent $2 billion over six years on grid hardening. U.S. utilities narrowly avoided similar cascading failures.

Long Term

The blackout drove development of NERC's geomagnetic disturbance standards and modern GIC monitoring. Hydro-Québec engineers believe their current grid would survive a repeat event.

Why It's Relevant Today

The 1989 storm remains the benchmark for grid vulnerability. The January 2026 storm, though severe, did not match its intensity—but demonstrated that forecasting gaps still leave operators with limited warning time.

Halloween Storms (2003)

October-November 2003

What Happened

Three massive sunspot groups produced 17 major flares over two weeks, including an X17 and X10 in rapid succession. CMEs traveling over 2,000 km/s triggered three consecutive G5 storms. The storms knocked out the Japanese ADEOS-II satellite, caused a power outage in Sweden, and disabled 12 transformers in South Africa.

Outcome

Short Term

Over half of Earth-orbiting satellites experienced effects. USAF satellite trackers lost position on most LEO assets for days.

Long Term

The Halloween storms established the modern standard for severe space weather events and drove investment in space weather forecasting infrastructure.

Why It's Relevant Today

The January 2026 S4 radiation storm was the first to exceed Halloween 2003 intensity in 23 years, marking a significant return to extreme conditions despite the solar cycle's declining phase.

Starlink Satellite Loss (2022)

February 2022

What Happened

A minor G1 geomagnetic storm—the lowest severity category—coincided with a Starlink deployment at 210 km altitude. Atmospheric density increased up to 50%, dramatically increasing drag on the 49 newly launched satellites. Despite safe-mode maneuvers, 38 satellites failed to reach operational altitude and burned up during reentry.

Outcome

Short Term

SpaceX lost approximately $50 million in satellites. The event demonstrated that even minor storms pose risks during specific operational phases.

Long Term

Satellite operators adjusted deployment procedures to account for space weather windows. The incident intensified research into thermospheric density forecasting.

Why It's Relevant Today

The 2022 loss showed that storm severity ratings alone don't capture operational risk. The January 2026 G4 storm carried similar satellite drag concerns, with operators preemptively entering safe mode.

15 Sources:
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NOAA Space Weather Prediction Center TIME Space.com CNN The Watchers European Space Agency Wikipedia NASA Science NOAA NESDIS NERC NOAA Space Weather Prediction Center NOAA Space Weather Prediction Center Wikipedia Wikipedia Space.com