The Planetary K-Index (Kp) is a standardized measure of geomagnetic activity that directly correlates with aurora visibility. Understanding the Kp scale is essential for planning successful Northern Lights viewing trips and interpreting aurora forecasts accurately.
The Kp index ranges from 0 to 9, with higher values indicating stronger geomagnetic activity and better aurora visibility at lower latitudes. For Alaska, even low Kp values (2-3) can produce visible aurora, while higher values (5+) create spectacular displays visible across the state.
CHECK CURRENT KP INDEXAurora visible in far northern Alaska (70°N+). Minimal activity, faint displays possible.
Good aurora visibility in Fairbanks and Interior Alaska. Moderate displays with good viewing opportunities.
Excellent aurora visible across all of Alaska, including Anchorage and South Central. Spectacular displays with high activity.
The Kp index is derived from magnetometer measurements at 13 stations worldwide. These measurements are averaged and converted to a standardized scale from 0 to 9, updated every 3 hours.
Alaska's position under the auroral oval means aurora can be visible at lower Kp values than mid-latitude locations. Fairbanks (64.8°N) can see aurora at Kp 2-3, while Anchorage (61.2°N) typically needs Kp 4-5.
Kp forecasts are most accurate for the next 24-48 hours. Longer-term forecasts (3-7 days) provide general trends but become less reliable. Real-time Kp values are updated every 3 hours from NOAA.