Geomagnetic storm today: is one in effect, and what does it mean for you?
A geomagnetic storm is a disturbance of Earth's magnetic field driven by the solar wind — a coronal mass ejection arriving, or a fast stream from a coronal hole. NOAA rates it G1 (minor, Kp 5) to G5 (extreme, Kp 9). The chips below say whether one is in effect now and what is forecast for three days; the card quotes SWPC's latest warning word for word; the table says how far the aurora reaches at each level and whether that includes your pin.
Storm level now and for three days
Reading NOAA…
What each level means
| Level | Kp | Oval overhead (magnetic lat.) | On the horizon from | How often | Other effects |
|---|---|---|---|---|---|
| G1 minor | 5 | 56° — northern Scotland, Denmark, Michigan's Keweenaw | Hamburg, Seattle, Chicago's north | ~900 days per 11-year cycle | Weak power-grid fluctuations; minor satellite drag |
| G2 moderate | 6 | 54° — Hamburg, Seattle, Toronto | London, Berlin, Detroit, Boston | ~360 days | Voltage alarms at high latitudes; HF radio fades |
| G3 strong | 7 | 52° — London, Berlin, Portland, Boston | Paris, Warsaw, New York, Chicago | ~130 days | GPS errors; false alarms on protection systems |
| G4 severe | 8 | 50° — Paris, Warsaw, New York, Chicago | Munich, Vienna, Washington DC, San Francisco | ~60 days | Widespread voltage control problems; satellite tracking issues |
| G5 extreme | 9 | 48° — Munich, Vienna, Washington DC, Denver | Rome, Madrid, Atlanta, Los Angeles (red only) | ~4 days | Grid collapse possible; HF radio out for days |
Levels, effects and frequencies are from NOAA's scales explanation; frequencies are per 11-year cycle; the latitudes are the oval's equatorward edge from the 2025 dipole (±1 Kp), and the horizon column is the same table read 600–900 km further toward the equator.
What makes one
A coronal mass ejection — a billion tonnes of plasma thrown off the Sun — arrives one to three days after it leaves, and if its magnetic field points south when it hits, it couples to Earth's and the storm begins. Fast streams from coronal holes give smaller, more predictable storms that recur every 27 days as the hole rotates back.
Watch, warning, alert
SWPC issues a watch when a CME is on its way (days ahead, by level), a warning when the field is expected to reach a Kp within hours, and an alert when it has. The quoted line above is the latest of these; the card names which.
The reference nights
10–11 May 2024: G5, Kp 9, the strongest storm since 2003; aurora photographed from Florida, Spain and Mexico, red overhead across the northern United States and Europe. 11–12 November 2025: G4, with aurora reported from the southern United States and southern Europe. 10–11 October 2024: G4, photographed under a first-quarter Moon — the night that shows the Moon is a discount, not a veto.
Why a storm at noon is a wasted storm
The oval brightens on the night side of Earth. A G3 that peaks at 14:00 your time can be over by dusk, and Europe and America rarely share a storm's best hour. The verdict page times the storm against your dark hours; this page only says whether one exists.
What it does to your gear
Nothing to a camera. GPS on your phone may wander by tens of metres during G3+; a compass app is fine (the field's direction moves by fractions of a degree, not by the ten degrees the photographs suggest).
Solar cycle 25
The cycle peaked in 2024–25; the declining phase that follows has historically given the largest storms (the great storms of 2003 came three years after maximum). The 27-day outlook on the left is the near-term; the years 2026–28 are the medium term.