Strong G3 Geomagnetic Storm Underway: Northern Lights Possible Far South Tonight

What happened today

This week the sun launched several CMEs toward Earth, mostly from the active sunspot Region 4549. The biggest left with an M6.7 flare at 15:48 UTC on 8 October. Forecasters at NOAA's Space Weather Prediction Center (SWPC) and the UK Met Office expected it and its neighbors to arrive late on 10 October or on 11 October, bringing G1 to G2 conditions. Our weekend outlook from this morning was based on that forecast.

The sun had other plans. At 14:34 UTC the solar wind monitor at the L1 point, about 1.5 million km sunward of Earth, recorded a sharp shock. Within one minute:

• solar wind speed jumped from about 410 to 520 km/s,
• density rose roughly tenfold,
• the interplanetary magnetic field (Bt) jumped from 10 to 26 nT, with Bz already pointing south at −16 nT.

The shock reached Earth's magnetic field 42 minutes later. NOAA recorded a sudden impulse of 56 nT at 15:16 UTC. Less than three and a half hours after the shock, the planetary K-index hit 7.

NOAA has since confirmed the arrival as the anticipated CME(s) from 7–8 October. The fastest of them, launched with the M6.7 flare on 8 October, needed only about 47 hours to arrive: an average speed of nearly 900 km/s, matching the winds measured at the peak, and about a day faster than modeled.

The storm by the numbers

Here's why this storm is strong rather than just lively. The three things that drive the aurora all lined up: fast wind, a strong magnetic field, and that field pointing south. (If those terms are new, start with what actually causes the northern lights.)

For comparison, a typical quiet day has a 350–400 km/s solar wind and a 5 nT field. Bz held between −20 and −29 nT for more than an hour, from about 16:00 to 17:10 UTC. That is the kind of sustained southward field that drives a storm to G3 and beyond. By 19:30 UTC Bz had swung to about zero while the field stayed strong at about 20 nT. That's the number to watch tonight. If Bz turns south again inside this CME, the aurora can flare up quickly. Our guide to reading the Kp index like a forecaster explains why Bz matters more than Kp in real time.

Who can see the northern lights tonight

NOAA's scale says that during a G3 storm, aurora may be seen as low as Illinois and Oregon. What you'll actually see depends on whether it's dark where you are while the storm is strong.

Europe: it's dark now

At 19:45 UTC it is 20:45 in the UK and Ireland, 21:45 in Central Europe and 22:45 in Finland. Europe is right under the storm in the evening, and the hours around local midnight are usually the most active.

• Overhead or high in the sky: Iceland, Norway, Sweden, Finland, the Baltic states and Scotland.
• Clearly visible to the north: Ireland, northern England and Wales, Denmark and the north of Germany and Poland.
• Possible low on the northern horizon, best by camera: southern England, the Netherlands, Belgium and central Germany, if the storm stays at Kp 7 or rises.

North America: it depends on the next few hours

The storm peaked during daylight in the Americas: 13:58 EDT and 10:58 PDT for the first Kp 7. Darkness arrives around 23:00 UTC on the East Coast and about 02:00 UTC on the West Coast. The CME is still passing, the field is still strong and more CMEs are on the way, so the chances are real but not guaranteed.

• If storming continues past dusk: all of Canada, Alaska and the northern states from Washington to Maine get a good show. Oregon, Idaho, Wyoming, South Dakota, Nebraska, Iowa, Illinois, Indiana, Ohio, Pennsylvania and New York are in range, mostly low in the north and best by camera.
• If it fades to G1–G2: the northern tier of states and Canada are still in play. See our weekend outlook for the G1–G2 visibility guide.

Southern Hemisphere

It's morning in Australia and New Zealand, so the aurora australis will only be visible there if the storm persists into their evening (from about 08:00 UTC on 11 October). Tasmania, Victoria and the South Island of New Zealand would then be best placed.

For photos, our iPhone and Samsung camera settings guide has a cheat sheet you can set up before you leave. If you're using a camera, see aurora photography settings for beginners. Faint aurora far south of the oval often looks colorless to the eye. Here's why.

Why the forecast said G1 and we got G3

At 12:30 UTC today, two hours before the shock, NOAA's 3-day forecast expected a maximum Kp of 4.67 for 10 October. That isn't a failure. It's the normal limit of CME forecasting:

• Arrival time is modeled from coronagraph images of the CME leaving the sun. Errors of ±6–12 hours are normal. This one came in roughly a day early, which suggests it was faster than the models estimated.
• Strength depends mostly on the CME's magnetic orientation. That can't be measured until the CME reaches the L1 monitor, 30–60 minutes before it hits Earth. This CME's field turned firmly south, and that turned a moderate event into a strong one.

The lesson: a storm watch means "be ready". Real-time Bz, not the 3-day forecast, tells you when to go outside.

What happens next

• Tonight (10 Oct UTC): NOAA's K7 warning runs until 23:59 UTC. The CME's magnetic structure is still passing, so more bursts of activity are possible whenever Bz dips south. Update: it did stay at storm level all evening, with Kp 6.67 for 18–21 UTC and 5.33 (G1) for 21–24 UTC.
• 11 October: NOAA's latest scales still show G2 for tomorrow. Other CMEs that left the sun on 7–9 October are still on their way, and a coronal-hole high-speed stream is adding to the disturbance.
• 12 October: the morning forecast called for G1–G2 on 12 October. That forecast was issued before today's arrival and is likely to be revised.
• Wildcard: Region 4549 fired an M6.4 flare at 15:10 UTC today, with a radio burst suggesting a shock at about 929 km/s. The region is now near the sun's western edge (N08W50), so any CME it launched would probably only hit Earth a glancing blow. Update: NOAA's analysis has the CME (first seen in coronagraph images at 15:48 UTC) passing just ahead of Earth, with only a possible graze late on 12 October.

Wider effects so far match a G3 storm: possible voltage corrections on high-latitude power grids, increased satellite drag and intermittent HF radio and GPS problems near the auroral zone. The two M6 flares also caused short R2 radio blackouts on the sunlit side of Earth. NOAA has reported nothing beyond normal G3 impacts.

The rest of the month, including the Kp 5 windows around 21–23 October and Halloween, is covered in our northern lights forecast for October 2026. This week's storms fit the pattern we describe in Northern Lights in 2026 and 2027: the declining phase of the solar cycle still delivers strong storms.

How to follow the storm live

• Our space weather bar at the top of this page shows the live NOAA Kp, solar wind speed and Bz.
• Aurora webcams under the oval show what the sky is doing right now in Finland, Norway, Iceland, Canada and Alaska. See our live aurora webcams page.
• NOAA SWPC publishes alerts, the real-time solar wind and the 30-minute OVATION aurora map.
• The UK Met Office issues space weather and aurora updates for the UK and Europe.