The Sun runs a weather system the size of the solar system, and Earth lives inside it. Here's the forecast.
NOAA's OVATION model turns live solar-wind measurements into a probability map of where aurora is happening in the next half hour or so. The green glow is the oval — it lives over the poles and bulges toward midnight, and on big storm nights it swells toward the equator.
Probability of visible aurora · brighter green = better odds · red tinge = very high. The dark region is night — where you'd actually see it.
One number for the whole planet's magnetic mood, updated every three hours from ground magnetometers worldwide. Below 4 is a quiet field; 5 and above is a geomagnetic storm, graded G1 to G5. The outlined bars are NOAA's forecast.
Measured at the L1 point, a million miles upstream — which gives Earth about 30 to 60 minutes of warning before whatever's coming arrives. Speed jumps and density spikes are how storms announce themselves.
Typical quiet wind blows 300–450 km/s. Above 600, auroras get interesting.
Protons per cubic centimeter. A sudden jump means a shock front just blew past the sensor.
NOAA's actual space weather bulletins, as they're issued — the same feed power-grid operators and satellite controllers watch.
Solar wind data comes from the DSCOVR and ACE spacecraft at L1. The Kp index is computed from a worldwide network of ground magnetometers. The OVATION aurora model is run by NOAA's Space Weather Prediction Center, the same office that issues every bulletin above. All of it is public data, updated continuously.