Solar Storms & Northern Lights

You just saw "geomagnetic storm watch" in the news. Here's what that actually means, whether you'll see aurora, and how to make the most of it.

Solar Storms 101

The sun is constantly releasing a stream of charged particles called the solar wind. Most of the time, Earth's magnetic field quietly deflects it and nothing dramatic happens. But the sun isn't always calm.

Sometimes the sun releases massive bursts of magnetized plasma called coronal mass ejections (CMEs). Think of them as billion-ton clouds of solar material hurtling through space at millions of miles per hour. When a CME slams into Earth's magnetic field, it compresses and distorts it. Charged particles funnel down along magnetic field lines toward the poles, colliding with oxygen and nitrogen in the upper atmosphere. Those collisions release energy as light — and that light is the aurora borealis.

The stronger the solar storm, the further south the aurora pushes and the brighter it glows. A minor storm might light up the sky over Fairbanks. A major one can paint the sky over Texas.

Types of Solar Events

Not all solar activity is the same. Three types of events matter most for aurora watchers:

Coronal Mass Ejections (CMEs) are the heavy hitters. A CME launches a massive cloud of magnetized plasma from the sun's corona. It takes 1 to 3 days to reach Earth, depending on speed. When it arrives, the impact can last hours or even days. CMEs are responsible for nearly every major aurora event you've seen in the news.

Solar flares are intense bursts of radiation — essentially explosions on the sun's surface. The light and X-rays from a flare reach Earth in about 8 minutes. Flares often accompany CMEs, but a flare by itself doesn't usually produce strong aurora. Think of the flare as the flash and the CME as the punch.

Coronal holes are regions where the sun's magnetic field opens outward, allowing a faster-than-normal solar wind stream to escape. These high-speed streams are weaker than CMEs, but they're predictable — coronal holes can persist for weeks and rotate with the sun, producing recurring aurora roughly every 27 days.

The G-Scale: How Strong Is the Storm?

When NOAA issues a geomagnetic storm watch, they use the G-scale — G1 through G5. Each level corresponds directly to a Kp index value, which is the number aurora forecasts use. Here's what each level means for you:

Most geomagnetic storm watches you see in the news are G1 or G2. Those are great news for anyone in Alaska or the northern Lower 48. G3 and above events happen several times per solar cycle and bring aurora to places that rarely see it. G5 events are extraordinary — the last one was in May 2024.

Solar Cycle 25 — Why 2025–2027 Is Special

The sun follows an approximately 11-year cycle of activity. We're currently in Solar Cycle 25, and it has turned out to be significantly stronger than scientists originally predicted. Early forecasts called for a modest cycle, but the sun had other plans — sunspot counts and CME frequency have exceeded expectations.

Solar maximum — the peak of the cycle — arrived in late 2024 and activity remains elevated through 2025, 2026, and likely into 2027. During solar maximum, the sun produces far more CMEs, which means more geomagnetic storms and more opportunities to see aurora.

How good is it right now? In May 2024, a G5 extreme geomagnetic storm produced aurora visible in all 50 US states — the strongest storm in over 20 years. Events of that magnitude are rare, but G1 through G3 storms have been occurring regularly throughout this solar maximum, giving aurora chasers in Alaska and the northern US frequent opportunities.

If you've been thinking about planning a northern lights trip, the next couple of years are about as good as it gets. After solar maximum passes, CME frequency will decline and aurora will become less common at lower latitudes until the next cycle ramps up in the 2030s.

How to Track Solar Activity

You don't need a physics degree to follow solar storms. Here's what to monitor:

NOAA Space Weather Prediction Center (SWPC) is the authority for geomagnetic storm forecasts in the US. They issue watches, warnings, and alerts when a CME is heading toward Earth. Their 3-day forecast gives you advance notice, though the exact timing and strength of a storm can shift right up until arrival.

The DSCOVR satellite sits at the L1 point between Earth and the sun, about a million miles out. It measures the solar wind in real time before it reaches Earth. When DSCOVR detects fast solar wind with a strong southward-pointing magnetic field (negative Bz), aurora is typically 30 to 60 minutes away. This is your short-range early warning system.

The two numbers to watch on real-time solar wind data are speed and Bz. Solar wind speed above 500 km/s is elevated. Bz below -10 nT (strongly southward) is the aurora trigger. When you see both together, conditions are primed for a good show. Alaska Glow incorporates these readings automatically into the forecast score, so you can check one place instead of monitoring raw data.

Are Solar Storms Dangerous?

The short answer: not to you. Earth's magnetic field and atmosphere shield us from the charged particles in solar storms. You can stand outside watching aurora all night without any health risk whatsoever.

What solar storms can affect is technology. During strong events (G3 and above), GPS accuracy can degrade, high-frequency radio communications may be disrupted, and satellites can experience drag and orientation issues. During extreme G5 events, there's a small risk to power grid infrastructure — the most famous example is the 1989 Quebec blackout, when a severe geomagnetic storm caused a cascading failure that left six million people without power for nine hours.

But for the vast majority of solar storms, the only thing you'll notice is a spectacular sky. Power grid operators and satellite controllers have improved their defenses significantly since 1989. When you see a geomagnetic storm watch in the news, the right response isn't worry — it's excitement.

What to Do When a Storm Is Forecast

A geomagnetic storm watch has been issued. Here's your game plan:

• Check the forecast timing. CME arrival time estimates can be off by several hours. If NOAA says arrival at 6 PM, the storm might hit anytime from noon to midnight. Stay flexible.
• Get away from city lights. Even a strong aurora is hard to see from a well-lit parking lot. Drive 15–30 minutes from the nearest city and find a spot with a clear view to the north (or in Alaska during a strong storm, look in every direction).
• Plan for the 10 PM – 2 AM window. Aurora can occur at any time after dark, but geomagnetic activity often peaks around magnetic midnight, which falls roughly between 10 PM and 2 AM local time in most of North America. This is your highest-probability window.
• Be patient. Aurora comes in waves called substorms. You might see nothing for an hour, then the sky erupts. Give it at least 60–90 minutes before giving up. Bring warm layers, a thermos, and a camp chair.
• Use your phone camera. Modern phone cameras (iPhone 15+ and recent Android flagships) capture aurora far better than the naked eye, especially early in a display when the aurora may be faint. Night mode or a 3-second exposure will often reveal vivid greens and purples before your eyes fully adjust.
• Monitor real-time data. Check for Kp updates and DSCOVR solar wind readings. If Bz has gone strongly southward and solar wind speed is elevated, the show is about to get better.