What is the Kp index
The Kp index measures global geomagnetic activity on a 0 to 9 scale. The higher it gets, the further south the aurora extends.
Kp 3-4: aurora visible in Iceland, northern Norway.
Kp 5-6: aurora visible in Scotland, southern Norway, southern Canada.
Kp 7-8: aurora occasionally visible in northern Spain (Pyrenees, Cantabria).
Kp 9: extreme storm, aurora visible far south.
Will I see aurora in my city?
Enter your city and we compute your approximate geomagnetic latitude, minimum required Kp and the forecast nighttime cloud cover.
Auroral oval map
Approximate aurora visibility line for current Kp. South of this line the aurora may be visible low on the northern horizon if skies are clear.
3-day Kp forecast
Best zones in Spain
With Kp >= 7 (strong geomagnetic storm) aurora can be observed from northern Spain. Three optimal areas:
| Zone | Geo lat. | Geomag lat. | Min Kp |
|---|---|---|---|
| Pyrenees of Lleida and Huesca | 42.7N | ~45N | 7 |
| Cantabrian coast (Asturias) | 43.4N | ~46N | 7 |
| Picos de Europa | 43.2N | ~45.8N | 7 |
| Northern Galicia (Cape Ortegal) | 43.7N | ~46.4N | 6-7 |
5 popular destinations
Northern lights: complete viewing guide
The aurora borealis is one of the most spectacular space weather phenomena in nature. It happens when charged particles from the solar wind interact with the Earth's magnetosphere and excite oxygen and nitrogen atoms in the upper atmosphere, producing the iconic green, red and violet hues between 100 and 300 km altitude.
The Kp index and solar activity
To predict where and when aurora will occur, scientists use the planetary Kp index, a quantitative measure of global geomagnetic disturbance. The scale runs from 0 (quiet) to 9 (extreme storm) and is updated every 3 hours from magnetic observatories worldwide. NOAA SWPC publishes real-time data and a 3-day forecast, which powers this page.
Solar cycle 25
The Sun has 11-year activity cycles. Solar cycle 25, which began in December 2019, peaked between 2024 and 2025, so 2026 and 2027 remain excellent years for aurora hunting: frequent coronal mass ejections (CMEs) and coronal holes trigger geomagnetic storms. At solar maximum it is relatively common to see aurora at latitudes as low as Madrid or Barcelona during Kp 8-9 events.
Best months
Aurora can be seen year-round but is only visible when the sky is dark. The best months are therefore September to March, with the March and September equinoxes especially productive (Russell-McPherron effect). In summer, at very high latitudes (>65 degrees), the midnight sun makes aurora unobservable even if it occurs.
How to photograph aurora
You need a manual-mode camera, a sturdy tripod, a fast wide-angle lens (f/2.8 or better), ISO 1600-6400 and 4-15 second exposures. Focus to infinity on a bright star. Bring spare batteries: extreme cold drains them fast.
What to wear
In Tromso, Yellowknife or Rovaniemi in mid-winter temperatures can drop below -25 C. Layering system: thermal base, fleece, down jacket, thermal pants, insulated boots, hat, heated gloves and scarf. Patience is also part of the kit: waiting 2-3 hours in the dark is normal.