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Geomagnetic K-indices

This chart is updated every 15 minutes at 1, 16, 31, and 46 minutes past the hour. Use the browser Refresh or Reload option to ensure the latest data is shown. Boulder, Colorado and Fredericksburg, Virginia are mid-latitude stations. College, Alaska is a high-latitude station. Estimated Planetary is a combined measure of several mid- and high-latitude stations.

K-index Warnings are issued when a Boulder K-indices of 4, 5, 6, and 7 or greater is expected.
K-index Alerts are issued when the Boulder K-index reaches 4, 5, 6, 7, 8, or 9 in a 3-hour period.

NOAA Boulder Magnetometer

Fredericksburg, College, and Estimated Planetary A- and K-index since 1994

A- and K-indices for last 2 years from all geomagnetic stations available at SWPC

Space Weather Data at SWPC -- Alerts and Forecasts, Models, Reports and Summaries, Indices, and Measurements as both plots and lists

Non-SWPC Sources of Geomagnetic Data