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

Tomorrow

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

Day After Tomorrow

00-03h
2
Clear sky
03-06h
1
Clear sky
06-09h
1
Clear sky
09-12h
1
Clear sky
12-15h
2
Clear sky
15-18h
3
Clear sky
18-21h
3
Clear sky
21-00h
4
Clear sky

27 Day Aurora Forecast

Aug 19
2
Aug 20
3
Aug 21
3
Aug 22
3
Aug 23
2
Aug 24
2
Aug 25
2
Aug 26
3
Aug 27
3
Aug 28
3
Aug 29
2
Aug 30
2
Aug 31
2
Sep 01
5
Sep 02
4
Sep 03
2
Sep 04
2
Sep 05
2
Sep 06
3
Sep 07
3
Sep 08
2
Sep 09
2
Sep 10
2
Sep 11
2
Sep 12
2
Sep 13
2
Sep 14
2