A plain-language northern lights outlook built from today's geomagnetic and solar wind measurements. Data refreshes once per day — for minute-by-minute alerts, watch the sky, not the screen.
At Kp 0, the aurora oval reaches polar regions only. You need dark, clear skies and a view toward the pole — the numbers can't see your local clouds.
Each bar is a 3-hour window. Kp 5 or higher (a G1 storm) is when auroras start reaching mid-latitudes; Kp 7+ can bring them deep into the northern US and central Europe.
It measures how disturbed Earth's magnetic field is. Higher Kp = the aurora oval expands toward the equator. Under 4, you need to be far north; 5+ brings mid-latitudes into play.
When the solar wind's magnetic field points south (negative Bz), it connects with Earth's field and pours energy in. A strongly negative Bz can spark auroras even at moderate Kp.
Fast solar wind (above ~500 km/s) and dense streams deliver more energy. Spikes often follow coronal mass ejections, 1–3 days after they leave the Sun.