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

Tomorrow

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

27 Day Aurora Forecast

Jul 15
4
Jul 16
4
Jul 17
3
Jul 18
2
Jul 19
2
Jul 20
2
Jul 21
2
Jul 22
2
Jul 23
2
Jul 24
2
Jul 25
2
Jul 26
2
Jul 27
2
Jul 28
3
Jul 29
2
Jul 30
2
Jul 31
2
Aug 01
2
Aug 02
2
Aug 03
2
Aug 04
3
Aug 05
4
Aug 06
4
Aug 07
3
Aug 08
2
Aug 09
2
Aug 10
2