Northern Lights Forecast Tonight

Four things decide it: whether tonight's Kp reaches your location's threshold, whether the sky is clear, whether it is properly dark, and how bright the moon is. Inside the auroral oval — northern Norway, Iceland, interior Alaska — a quiet night can be enough. From mid-latitudes it takes a geomagnetic storm. Check the Kp timeline above against your own location's threshold, then the cloud forecast. If tonight is no, the locations with the best chance are listed below.

Usually between 22:00 and 02:00 local time (10pm–2am). That window sits around magnetic midnight, when substorms most often peak — and magnetic midnight is not always the same as clock midnight. Aurora can appear at any dark hour; this is when it appears most often. Darkness sets the limits, not the aurora. Above the Arctic Circle there is no astronomical night around midsummer, and nothing to see whatever the activity. Your location page shows the hours that are actually dark tonight.

• Tromsø

A ring around the geomagnetic pole called the auroral oval, near 67–68° geomagnetic latitude. Northern Norway, northern Sweden, Iceland and interior Alaska sit inside or on its edge. Storms push the oval equatorward, which is how aurora occasionally reaches Germany, the UK or the northern United States. The North Pole is not the best place. The geographic and magnetic poles lie inside the polar cap, poleward of the oval, where aurora is less frequent than in the ring below it. Each of those countries has a page with its regions and their thresholds.

• Tromsø
• Abisko
• Reykjavík
• Fairbanks

There is no single number — it depends on your geomagnetic latitude, which is not your map latitude. The auroral oval's equatorward edge sits near 66° geomagnetic at Kp 0 and moves roughly 2° further south with each step up the scale, reaching about 48° at Kp 9. Kp describes how large the oval is, not whether aurora is above you — inside the oval it matters much less than cloud. Every location page on this site prints that location's own threshold.

• Tromsø

The dark half of the year. Aurora happens all year; what changes is whether the sky is ever dark enough to see it. In interior Alaska the University of Alaska Fairbanks puts the season at roughly 21 August to 21 April, and the further north you go the more of the summer is lost to daylight. Activity itself is statistically higher around the March and September equinoxes — in interior Alaska about twice the chance of the solstices. A tilt in the odds, not a promise for any particular night. Destination pages show each place's own best months.

• Fairbanks
• Reykjavík

Light produced high in the atmosphere when solar particles strike oxygen and nitrogen, typically 110–200 km (68–125 miles) up. It can occur as low as 80 km and, rarely, far higher. The same thing happens around the southern geomagnetic pole, where it is called the aurora australis. The colours come from different gases at different heights: green at 557.7 nm from atomic oxygen around 100–150 km, red at 630.0 nm from oxygen above 200 km in strong storms, and blue or purple from nitrogen below about 120 km.

The solar wind. When the interplanetary magnetic field carried by it turns southward — the Bz component — it reconnects with Earth's own field and lets solar-wind energy into the magnetosphere. That energy accelerates particles down the field lines into the auroral oval, where they hit the atmosphere. Bz cannot be predicted in advance. It is measured by satellites at L1, about 1.5 million km (930,000 miles) sunward, which gives 15–60 minutes of real warning — the reason a three-day forecast tells you a storm is coming, not that you will see anything.

Get away from the city lights, find an open view toward the pole — north in the Northern Hemisphere — and give your eyes 20–30 minutes to adapt. Then wait: displays come in bursts, and half an hour of nothing is normal. Keep your phone screen off, because it resets your night vision. Check cloud before you drive anywhere — cloud blocks aurora at any Kp — and pick a night near new moon, since a bright moon washes out faint displays. In a strong storm the aurora can reach overhead or even south of you.

Hold the phone still — a tripod, a wall, a car roof — turn the flash off and switch on night mode: Night mode on iPhone, Night Sight on Pixel. It holds the exposure open for seconds. Your eyes cannot collect light over time; a sensor can, so the phone records colour you could not see. In the dark your vision runs on rod cells, which register light but carry no colour information. This is why a display that looks grey overhead comes out green in the photo, and why red aurora barely registers to the eye at all.