Can I see the northern lights tonight?

How the verdict is worked out

The northern lights hang in a ring around the north magnetic pole, the auroral oval, about 100 to 400 km above the ground. Whether you can see them comes down to how close that ring gets to you tonight, and the closeness depends on your magnetic latitude, not the latitude on a map.

Step 1: your magnetic latitude

Earth's magnetic field is tilted and lopsided. The axis of its best-fitting dipole meets the surface at 80.9°N, 72.8°W this year, according to the IGRF-14 model published by the International Association of Geomagnetism and Aeronomy, so the north magnetic pole region leans toward Canada. On top of that tilt the real field has big regional bumps. To handle both, this page traces Earth's magnetic field line from your location up to its highest point using the full IGRF-14 model and turns that into an apex latitude, the same kind of coordinate the auroral oval is mapped in. New York, at 40.7°N, comes out at 48.7° magnetic; London, eleven degrees further north on the map, comes out lower, which is why aurora reaches the US Northeast more often than southern England.

Step 2: the Kp your location needs

The equatorward edge of the oval sits near 66.5° magnetic latitude on a quiet night and moves about 2.05° (roughly 230 km) toward the equator for each step of the Kp index, reaching about 48° at Kp 9. That relation comes from the standard Kp-to-latitude table that aurora forecasters use. When the edge is over you, the aurora is overhead. Because the lights are high up, you can also see them low on the horizon from about 4.5° (500 km) outside the edge: we checked that distance against city-by-city visibility lists for Kp 3 to 7 and it matches to within about one Kp step.

Step 3: tonight's forecast and darkness

The page then reads NOAA's 3-hour Kp forecast and takes the highest value during your dark hours tonight, from nautical dusk to nautical dawn (the Sun more than 12° down). If that Kp reaches what you need, the verdict says possible, good chance or overhead; if it falls short, unlikely. It cannot see clouds, so check your local weather too.

What time are the northern lights tonight?

The aurora is busiest around magnetic midnight, the moment your location faces straight down Earth's magnetic tail, away from the Sun. Energy stored in the tail is released in substorms, and they are most likely in the two or three hours around that time. Magnetic midnight is not clock midnight: in New York tonight it falls at about 12:47 AM, in Britain around 11 PM GMT and in northern Scandinavia around 10 PM CET. The best hours shown above are those hours, cut to the time when it is properly dark.

Storms do not read the clock, though. When a coronal mass ejection hits, aurora can flare up at dusk or just before dawn, and a single night can bring several bursts an hour or two apart. If the forecast is good, step outside every 30 minutes from dusk.

Where to see the northern lights tonight

• Face north (south in the Southern Hemisphere), toward the direction shown in the sky view. From mid-latitudes the aurora starts as a glow just above the horizon, so a low, open horizon matters: water, fields, a ridge.
• Get away from lights. A town's glow can hide a moderate display completely. Dark-sky parks and rural roads an hour from a city are worth the drive on a good night.
• Let your eyes adjust. It takes 15 to 20 minutes to see faint glows. Use a red light and keep your phone screen dim.
• Watch for a grey arc. Faint aurora looks like a pale cloud that does not move with the wind, or an arc over the north. Point your phone camera at it to check.
• Check the Moon. A bright Moon high in the sky washes out faint aurora. A thin crescent or a Moon below the horizon helps. See the Moon phase today.

Photographing the aurora with a phone

Modern phones are very good at this, often better than the eye. Turn off the flash. On iPhone, Night mode starts automatically in the dark; hold steady or brace the phone and let it run the full 3 to 10 seconds, or use a small tripod for up to 30 seconds. On Android, use Night Sight or Night mode, or Pro mode with ISO 800 to 3200, a 2 to 8 second exposure and manual focus set to infinity. Shorter exposures keep fast-moving rays sharp; longer ones catch faint glows. Include something on the ground, such as trees, a lake or a building, for scale.

Why the colours look different in photos

Green comes from oxygen 100 to 250 km up, red from oxygen higher still, and purple or pink at the lower edge from nitrogen. Your eyes switch to rod vision in the dark, which is sensitive but colour-blind, so faint aurora looks grey or pale green. The camera's sensor has no such limit. When people in Britain or the US see a red sky in their photos during a big storm, they are usually seeing the high red tops of an aurora that is hundreds of kilometres to the north.

In the Southern Hemisphere

The same rules work in reverse for the aurora australis. Tasmania, New Zealand's South Island and southern Victoria are the best-placed populated areas; Hobart needs about Kp 4. Face south, away from town lights, and the same magnetic-midnight timing applies.

Related: Aurora forecast and live map · Planets visible tonight · Is it a full moon tonight?