On the night of 13 March 1989, the entire province of Quebec went dark. In roughly ninety seconds, a geomagnetic storm triggered by an eruption on the Sun collapsed the Hydro-Quebec power grid, cutting electricity to about six million people for around nine hours. It remains the clearest warning the modern world has of what space weather can do — and more than three decades later, we are far more exposed, not less.
As Solar Cycle 25 pushed through its maximum between 2024 and 2026, the Sun has been more active than forecasters originally expected. Understanding how solar storms reach Earth, what they threaten, and how operators are preparing has moved from a niche scientific curiosity to a genuine question of national infrastructure — especially for a high-latitude country like Canada.
What space weather actually is
Space weather is the catch-all term for conditions on the Sun and in the space around Earth that can affect technology and, occasionally, human health. Most of the drama comes from two kinds of solar outbursts. Solar flares are sudden flashes of radiation that reach Earth in about eight minutes and can disturb radio and GPS signals almost instantly. Coronal mass ejections, or CMEs, are far larger — billions of tonnes of magnetised plasma hurled into space, arriving one to three days later. When a CME slams into Earth’s magnetic field, it drives a geomagnetic storm.
Those storms are graded on a five-step scale run by the U.S. National Oceanic and Atmospheric Administration, from a minor G1 to an extreme G5. You can follow live conditions and forecasts directly from NOAA’s Space Weather Prediction Center, which issues the same alerts that grid and satellite operators rely on.
| Scale | Severity | Typical effects |
|---|---|---|
| G1 | Minor | Weak grid fluctuations; aurora at high latitudes |
| G2 | Moderate | Voltage alarms; satellite drag increases |
| G3 | Strong | False grid alarms; GPS errors; aurora further south |
| G4 | Severe | Widespread voltage control problems; navigation degraded for hours |
| G5 | Extreme | Grid collapse risk; satellites lost; continent-wide GPS disruption |
The storms that put us on notice
The 1989 Quebec blackout is the case study every grid engineer knows, but it is no longer the most recent wake-up call. In May 2024, a barrage of CMEs produced the so-called Gannon Storm, the first G5 extreme event NOAA had flagged since the Halloween storms of 2003. Skywatchers saw aurora as far south as Mexico and Florida; less visibly, farmers using satellite-guided tractors reported their equipment wandering off-line as precision GPS drifted. Barely a year later, on 1–2 June 2025, another Earth-directed eruption drove a G4 severe storm, proof that the active period was far from over.
Satellite operators felt it too. In an earlier storm in February 2022, a single geomagnetic event thickened the upper atmosphere enough to drag dozens of freshly launched Starlink satellites back to Earth before they reached their orbits. As megaconstellations balloon into the tens of thousands of spacecraft, that kind of atmospheric drag becomes an operational and financial risk, not a footnote.
Why the grid is the biggest worry
The reason a storm on the Sun can black out a province comes down to physics playing out in metal. When Earth’s magnetic field convulses during a storm, it induces slow-moving electrical currents — geomagnetically induced currents, or GICs — in any long conductor. Power lines, pipelines and railway tracks all qualify. In the worst cases these currents can reach around a hundred amperes, quietly saturating the iron cores of the large transformers that anchor a grid, overheating them and, in extreme events, destroying them.
That is the frightening part. A blackout can be restored in hours; a fried extra-high-voltage transformer can take months to replace, because each is effectively custom-built and few spares exist. Analysts modelling a once-in-a-century, Carrington-class storm have warned that a direct hit could cause damage measured in the trillions of dollars and leave parts of a continent without reliable power for weeks. Canada is unusually exposed here: high-latitude grids sit closer to the auroral zone where GICs are strongest, and long transmission lines carrying hydro power across vast distances are exactly the kind of conductor that soaks them up. Building a more storm-resilient grid is part of the same broader push toward cleaner, smarter energy infrastructure, from next-generation solar technology to large-scale carbon removal.
GPS, aviation and everyday technology
Grids grab the headlines, but the disruptions most people would actually notice are subtler. Geomagnetic storms churn the ionosphere, the charged layer of the upper atmosphere that GPS signals must pass through. That turbulence, known as scintillation, can throw satellite-navigation fixes off by tens of centimetres — trivial for finding a restaurant, serious for automated farming, surveying, marine docking or drone delivery. Airlines flying polar routes between North America and Asia reroute during severe storms because high-frequency radio, their backup communication over the pole, degrades badly. High-altitude crews and astronauts also face elevated radiation doses.
Ironically, the same computing and artificial-intelligence advances driving other parts of the economy are becoming central to predicting these events, as forecasters lean on the kind of massive AI computing infrastructure now being built to model the Sun’s behaviour more precisely.
Can we prepare?
Encouragingly, yes — and this is where the 1989 lesson has paid off. Grid operators now receive NOAA and national space-weather alerts and can take defensive steps when a severe storm is forecast: reducing loads, postponing maintenance that would take equipment offline, and reconfiguring the network so no single transformer carries too much. Some utilities have installed devices to block GICs from reaching their most critical transformers. Satellite operators can put spacecraft into safe modes, delay launches, and raise orbits ahead of the atmospheric swelling a storm brings.
The gap is warning time. We get one to three days from a CME’s launch, but the crucial detail — the orientation of its magnetic field, which determines how damaging it will be — is only measured reliably by spacecraft about a million and a half kilometres upstream of Earth, roughly fifteen to sixty minutes before impact. Closing that gap with better forecasting is one of the most active frontiers in the field.
Frequently asked questions
Can a solar storm really cause a blackout?
Yes. The clearest example is the March 1989 storm that collapsed the Hydro-Quebec grid and left about six million people without power for roughly nine hours. Severe storms induce currents that can overload and damage grid transformers.
Are solar storms getting worse in 2025 and 2026?
The Sun runs on an eleven-year cycle, and Solar Cycle 25 reached its maximum around 2024 to 2026 — more intensely than first forecast. Major storms in May 2024 and June 2025 show the risk is elevated during this window, though it will ease as the cycle winds down.
Do solar storms hurt people on the ground?
For people at the surface, the direct health risk is essentially nil; Earth’s atmosphere and magnetic field absorb the radiation. The real exposure is to technology, plus modestly higher radiation doses for astronauts and passengers on high-altitude polar flights.
How much warning do we get?
A coronal mass ejection takes one to three days to reach Earth, but its most important property is only confirmed by monitoring spacecraft roughly fifteen to sixty minutes before it arrives, which is why improving forecasts matters so much.
