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

1

09-12h

1

12-15h

1

15-18h

1

18-21h

2

21-00h

2

Tomorrow

00-03h

2

03-06h

1

06-09h

1

09-12h

1

12-15h

1

15-18h

1

18-21h

2

21-00h

2

Day After Tomorrow

00-03h

2

03-06h

1

06-09h

1

09-12h

1

12-15h

1

15-18h

1

18-21h

2

21-00h

2

27 Day Aurora Forecast

Oct 18

4

Oct 19

4

Oct 20

3

Oct 21

3

Oct 22

3

Oct 23

2

Oct 24

2

Oct 25

3

Oct 26

2

Oct 27

2

Oct 28

2

Oct 29

2

Oct 30

2

Oct 31

2

Nov 01

2

Nov 02

3

Nov 03

2

Nov 04

2

Nov 05

2

Nov 06

4

Nov 07

3

Nov 08

3

Nov 09

2

Nov 10

2

Nov 11

2

Nov 12

2

Nov 13

2