Northern Lights Tonight

Is it worth going out tonight?

Before you drive somewhere dark, spend thirty seconds on the live numbers — they tell you far more than any static "tonight's chance" percentage. Three readings decide most nights. Look for the Bz to be pointing south (a negative value, ideally below −5 to −10 nT and holding there), the solar wind speed to be elevated (roughly 500 km/s or higher rather than a quiet ~350 km/s), and the KP index to be climbing toward the level your latitude needs. When all three lean the right way at the same time, it's genuinely worth going out. When Bz is stubbornly northward, even a high wind speed usually fizzles.

The best hours: aim for magnetic midnight

The aurora doesn't wait for a convenient time. Statistically, the strongest and most overhead displays cluster in the hours around magnetic midnight — usually somewhere between about 10 pm and 2 am local time, when your location has rotated to the midnight side of Earth's magnetic tail. That's when the auroral oval typically dips furthest toward the equator and substorms are most likely to erupt. Two practical rules follow: give yourself a window rather than a single moment, and don't give up after ten quiet minutes. Aurora arrives in bursts — a flat, empty sky can brighten into moving curtains within minutes when a substorm breaks, then fade again.

Clear, dark skies away from light pollution

Space weather sets the ceiling; the sky at your feet decides what you actually see. Two local factors can cancel out a perfect KP reading. The first is cloud — aurora happens around 100 km up, far above the weather, so an overcast layer simply hides it; check a normal cloud forecast alongside the space-weather numbers. The second is light pollution. From the middle of a bright city, only the strongest storms punch through the glow. Driving fifteen to thirty minutes to a dark site with a clear, unobstructed view toward the northern horizon (or south, if you're in the far southern hemisphere) transforms a marginal night. Let your eyes dark-adapt for fifteen to twenty minutes, keep your phone screen dim, and remember a camera or phone on a long exposure will pick up colour and faint arcs that look grey to the naked eye.

Rough KP-by-latitude guide

The single most common question is "how high does KP need to be for me?" The honest answer is that it depends on your geomagnetic latitude, not just the number on a map. As a rough guide: high-latitude spots like northern Norway, Iceland, northern Scandinavia, Alaska and northern Canada can catch aurora on the horizon at KP 2–3 on an ordinary active night. Places such as Scotland, the northern United States, southern Scandinavia and the northern parts of the lower Great Lakes usually want KP 5 or more — a G1 geomagnetic storm — before the show reaches them. Mid-latitudes further south typically need a strong storm, KP 6–7+ (G2–G3 and up), and even then the aurora often sits low on the northern horizon rather than overhead. Treat these as starting points, not promises: a sustained southward Bz can drag the oval lower than the KP number alone suggests, which is exactly why the live readings beat a fixed table.

Northern lights tonight FAQ