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

3.33

03-06h

2

06-09h

2

09-12h

3

12-15h

3

15-18h

3.33

18-21h

3.67

21-00h

4

Tomorrow

00-03h

4

03-06h

4

06-09h

4.67

09-12h

4.67

12-15h

4.67

15-18h

4

18-21h

3.67

21-00h

3.33

Day After Tomorrow

00-03h

3

03-06h

2.67

06-09h

2.33

09-12h

2.33

12-15h

2

15-18h

2

18-21h

2

21-00h

2.33

27 Day Aurora Forecast

Sep 07

4

Sep 08

5

Sep 09

3

Sep 10

2

Sep 11

2

Sep 12

2

Sep 13

2

Sep 14

4

Sep 15

4

Sep 16

4

Sep 17

2

Sep 18

2

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