The K-index quantifies disturbances in the horizontal component of earth’s magnetic field with an integer in the range 0–9 with 1 being calm and 5 or more indicating a geomagnetic storm. It is derived from the maximum fluctuations of horizontal components observed on a magnetometer during a three-hour interval.

The official planetary Kp-index is derived by calculating a weighted average of K-indices from a network of geomagnetic observatories. Since these observatories do not report their data in real-time, various operations centers around the globe estimate the index based on data available from their local network of observatories. The Kp-index was introduced by Bartels in 1939.

Today

00-03h
2
03-06h
2
06-09h
1
09-12h
1
12-15h
2
Clear sky
15-18h
2
Clear sky
18-21h
3
Clear sky
21-00h
2
Clear sky

Tomorrow

00-03h
2
Clear sky
03-06h
3
Clear sky
06-09h
2
Clear sky
09-12h
2
Clear sky
12-15h
1
Clear sky
15-18h
1
Clear sky
18-21h
2
Clear sky
21-00h
2
Clear sky

Day After Tomorrow

00-03h
2
Clear sky
03-06h
3
Clear sky
06-09h
2
Clear sky
09-12h
2
Clear sky
12-15h
1
Clear sky
15-18h
1
Clear sky
18-21h
2
Clear sky
21-00h
2
Clear sky

27 Day Aurora Forecast

May 20
3
May 21
3
May 22
3
May 23
2
May 24
2
May 25
2
May 26
2
May 27
2
May 28
3
May 29
4
May 30
3
May 31
3
Jun 01
2
Jun 02
2
Jun 03
2
Jun 04
2
Jun 05
2
Jun 06
2
Jun 07
2
Jun 08
2
Jun 09
2
Jun 10
2
Jun 11
2
Jun 12
2
Jun 13
2
Jun 14
2
Jun 15
2