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
1
03-06h
0
06-09h
0
09-12h
1
12-15h
1
15-18h
1
18-21h
2
Clear sky
21-00h
2
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
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

27 Day Aurora Forecast

Sep 14
2
Sep 15
2
Sep 16
2
Sep 17
2
Sep 18
2
Sep 19
2
Sep 20
2
Sep 21
2
Sep 22
2
Sep 23
3
Sep 24
3
Sep 25
4
Sep 26
4
Sep 27
5
Sep 28
4
Sep 29
3
Sep 30
2
Oct 01
2
Oct 02
2
Oct 03
2
Oct 04
2
Oct 05
2
Oct 06
2
Oct 07
2
Oct 08
2
Oct 09
2
Oct 10
2