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.

EXTENDED NORTHERN LIGHTS FORECAST

Today

00-03h

3

03-06h

1.67

06-09h

1.67

09-12h

1.67

12-15h

3.33

15-18h

3.33

18-21h

3.33

21-00h

4.67

Tomorrow

00-03h

3.67

03-06h

2

06-09h

2

09-12h

2.67

12-15h

2.67

15-18h

2.67

18-21h

2.67

21-00h

3

Day After Tomorrow

00-03h

2.67

03-06h

2

06-09h

2.33

09-12h

2.33

12-15h

2.33

15-18h

2.33

18-21h

2.33

21-00h

2.67

27 Day Aurora Forecast

Sep 14

4

Sep 15

4

Sep 16

5

Sep 17

5

Sep 18

3

Sep 19

2

Sep 20

2

Sep 21

2

Sep 22

2

Sep 23

2

Sep 24

5

Sep 25

5

Sep 26

5

Sep 27

4

Sep 28

2

Sep 29

2

Sep 30

2

Oct 01

2

Oct 02

2

Oct 03

2

Oct 04

3

Oct 05

4

Oct 06

4

Oct 07

3

Oct 08

3

Oct 09

2

Oct 10

2