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This chart is updated every 15 minutes at 1, 16, 31, and 46 minutes past the hour.
The Estimated 3-hour Planetary Kp-index is derived at the NOAA Space Weather Prediction Center using data from the following ground-based magnetometers: Boulder, Colorado; Chambon la Foret, France; Fredericksburg, Virginia; Fresno, California; Hartland, UK; Newport, Washington; Sitka, Alaska. These data are made available thanks to the cooperative efforts between SWPC and data providers around the world, which currently includes the U.S. Geological Survey, the British Geological Survey, and the Institut de Physique du Globe de Paris.
K-index Watches are issued when the highest predicted K-index for a day is K = 5, 6, 7, or >= 8 and is reported in terms of the NOAA G scale.
K-index Warnings are issued when NOAA K-indices of 4, 5, 6, and 7 or greater is expected.
K-index Alerts are issued when the NOAA K-index reaches 4, 5, 6, 7, 8, or 9 in a 3-hour period.
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
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