Outdoors · 6 min read
Can You See the Northern Lights Tonight? The Kp Index Explained
In May 2024, people across the UK and in large parts of the US saw the northern lights. Since then, every solar storm alert sends millions of people searching for one question: can I see the aurora tonight? The answer depends on two things: how strong the storm is, and whether your sky is clear.
Photo: the aurora seen from Greater London in May 2024, Saifur7599, Wikimedia Commons (CC BY 4.0)
- Kp index: a 0 to 9 scale of geomagnetic activity; the higher the number, the further south the aurora can be seen.
- US rule of thumb: at Kp 7 the aurora has been seen as far south as Illinois and Oregon, and at Kp 9 as far as Florida and southern Texas.
- UK: Scotland, Northern Ireland and northern England have the best chances; in the south it is often only visible through a camera.
- Clear skies: clouds block the view completely, so check the cloud forecast before heading out.
- Tip: a phone camera in night mode often picks up more color than your eyes do.
In this article
What causes the northern lights?What is the Kp index?Can you see the northern lights from the UK?The storm of May 2024Clear skies matter as much as the stormHow to get the best viewFrequently asked questionsWhat causes the northern lights?
The sun constantly sends out a stream of charged particles, the solar wind. When a large burst of particles reaches Earth, it disturbs Earth's magnetic field and causes a geomagnetic storm. Particles are guided toward the polar regions, where they collide with oxygen and nitrogen high in the atmosphere and make them glow. Usually this happens in a ring around the North Pole, over places like Alaska, northern Canada, Iceland and northern Norway. During a strong storm, that ring expands south, and the aurora becomes visible much further from the pole.
What is the Kp index?
The Kp index measures how disturbed Earth's magnetic field is, on a scale from 0 (quiet) to 9 (extreme storm), based on measurements from magnetic observatories around the world. NOAA's Space Weather Prediction Center links Kp values to its geomagnetic storm scale, from G1 to G5, and describes how far south the aurora has been seen at each level.
| Kp | NOAA storm level | How far south aurora has been seen (US) |
|---|---|---|
| 5 | G1 (minor) | Commonly visible at high latitudes, such as northern Michigan and Maine |
| 6 | G2 (moderate) | As low as New York and Idaho |
| 7 | G3 (strong) | As low as Illinois and Oregon |
| 8 | G4 (severe) | As low as Alabama and northern California |
| 9 | G5 (extreme) | As low as Florida and southern Texas |
Source: NOAA Space Weather Prediction Center, space weather scales.
These are the furthest points where the aurora has been seen at each level, not a guarantee. At the southern edge, the aurora usually appears as a faint glow low on the northern horizon, not the dancing curtains you see in photos from the Arctic.
Can you see the northern lights from the UK?
Yes, especially from Scotland, Northern Ireland and northern England, which are closer to the auroral zone. During the strong storm of May 10, 2024, the Met Office reported sightings from top to tail across the country, but further south the aurora is often faint and sometimes only shows up through a camera. In the UK, alert services such as AuroraWatch UK, run by Lancaster University, send a notification when activity rises, and the Met Office publishes a space weather forecast.
The storm of May 2024
The geomagnetic storm of May 10-11, 2024 reached G5, the top of NOAA's scale, the first G5 storm since October 2003. It was caused by several eruptions from the sun that reached Earth one after another. With clear skies over large parts of Europe and North America, it became one of the most widely seen aurora displays in decades. The sun's activity peaked around 2024 in its roughly 11-year cycle, but strong storms remain possible for years after the peak.
Clear skies matter as much as the storm
The aurora happens far above the clouds, so a thick cloud layer hides it completely, no matter how strong the storm is. Before you head out, check the cloud cover for tonight in your local forecast, for example for Seattle, Chicago, Edinburgh or London. A few hours of clear sky can be enough. A bright moon and city lights also wash out a faint aurora.
How to get the best view
Find a dark spot away from city lights with an open view to the north. Give your eyes 15 to 20 minutes to adjust to the dark and avoid looking at a bright screen. Take photos with your phone in night mode, or with a camera on a tripod and a long exposure: cameras often capture pink and green colors that look gray or white to the naked eye. Dress warmly, because aurora watching means standing still for a long time, often late at night. Our guide to feels-like temperature explains why it feels colder than the thermometer says.
Frequently asked questions
What Kp do you need to see the northern lights?
It depends on where you are. According to NOAA's scale, the aurora has been seen as far south as New York and Idaho at Kp 6, Illinois and Oregon at Kp 7, Alabama and northern California at Kp 8, and Florida and southern Texas at Kp 9. In the UK, Scotland has the best chances.
Can you see the northern lights in the UK?
Yes, mostly in Scotland, Northern Ireland and northern England during a geomagnetic storm. In strong storms, such as May 2024, it can be seen across the whole country, although in the south it is often faint.
Why does the aurora look better on photos?
A camera can collect light for longer than your eyes, so it picks up colors that look gray or white to the naked eye, especially when the aurora is faint.
Do clouds block the northern lights?
Yes. The aurora forms far above the clouds, so a thick cloud layer hides it completely. Check the cloud forecast for your location before going out.
Check the weather in Seattle or search another place on the locations page.