# DOI: https://doi.org/10.5880/Kp.0001 # LICENCE: CC BY 4.0, please cite: # Matzka, J., Bronkalla, O., Tornow, K., Elger, K. and Stolle, C., 2021. # Geomagnetic Kp index. V. 1.0. GFZ Data Services, # https://doi.org/10.5880/Kp.0001 # Matzka, J., Stolle, C., Yamazaki, Y., Bronkalla, O. and Morschhauser, A., # 2021. The geomagnetic Kp index and derived indices of geomagnetic activity. # Space Weather, https://doi.org/10.1029/2020SW002641 # The Kp index was introduced by Bartels (1949) and is produced by Geomagnetic # Observatory Niemegk, GFZ German Research Centre for Geosciences. Quietest Days Most Disturbed Days Month Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8 Q9 Q10 D1 D2 D3 D4 D5 Jan 1940 28 21 26 14 27 23 15A 22A 20A 13A 3 18 31 12 10 Feb 1940 18 19 17 14 28 10A 27A 15A 16A 4A 1 25 20 2* 21* Mar 1940 18 15 17 11 6 5 4 7 2 10 30 25 24 31 29 Apr 1940 10 9 7 8 12 18 11 19 23A 17A 3 25 1 26 2 May 1940 6 31 30 8 4 2 3 5 16K 7 24 18 22 26 27 Jun 1940 4 20 1 13 11 21 12 29K 3K 28K 25 6 14 7 26 Jul 1940 18 27 2 17 20 19 12 26 8K 28 13 10 4 14 30* Aug 1940 24 15 17 16 30 25 23 21 13A 14A 9 3 26* 6* 11* Sep 1940 23 17 19 10 18 12 11 13 24 22A 27 28 7 26 3 Oct 1940 23 24 14 13 17 30 10A 31A 29K 5A 7 8 1 26 3* Nov 1940 10 11 8 24 28K 18 2K 19A 6A 20A 13 29 22 25 26 Dec 1940 8 7 19 6 18K 17A 5A 11A 24A 10A 20 30 21 2 31 Jan 1941 14 5 31 15 3K 21K 29 2A 13A 12A 17 24 18 25 26 Feb 1941 27 12 1 11 2A 19A 18A 4A 28A 10A 22 23 21 7 15 Mar 1941 27 26 17 16A 18A 25A 10A 24A 12A 13A 1 14 30 31 28 Apr 1941 30 23 14 27 5 4 22 15K 1A 13A 24 25 19 10 11 May 1941 20 19 11K 12 7K 5 14 2 27 3 22 17 23 24* 21* Jun 1941 4 2 3 16 7 5 8 23 25 30 13 10 20 15 11 Jul 1941 27 26 28 29 13 14 30 15 18 31K 5 7 6 21 4 Aug 1941 9 23 16 10 17 20 15 22 8 18 4 27 2 29 30 Sep 1941 5 6 4 26 12 22 3K 10K 11A 28A 18 19 20 21 24 Oct 1941 7 4 3 18 21 6 1 17 2K 29K 31 11 22 12 15* Nov 1941 15 26 2 14 16 25 24 3 4 30 1 28 6 17 10 Dec 1941 11 21 22 25 12 20 19 31 10 30A 1 2 14 4* 18* Jan 1942 31 1 21 29 24 14 8 26 27 9 4 5 18* 17* 3* Feb 1942 19 12 8 9 4 18 1 26 13K 14K 23 6 24 28 5 Mar 1942 28 16 12 25 27A 24A 17A 31A 11A 30A 1 5 3 2 9 Apr 1942 25 22 26 7 21 15 29 10K 6K 12 4 17 11 3 18 May 1942 26 9 31 13 12 19 8 7 25 17 14* 28* 5* 27* 4* Jun 1942 2 10 9 22 7 1 4 27 8 26 11 13* 30* 19* 14* Jul 1942 4 3 2 19 18 5 7 6A 22A 24A 11 8 15 27 25 Aug 1942 8 29 28 14 4 13 1 5 9 2 23 16 10 19 18 Sep 1942 29 30 25 28 9 3 26K 24A 27A 10A 12 21 17 14 18 Oct 1942 1 24 22 23 6 9A 10 21A 26A 8A 29 3 2 30 28 Nov 1942 22 9 19 16A 5A 17A 6A 30A 7A 3A 24 26 25 28 29* Dec 1942 30 31 18 19 17 6 29 5 2K 13 21 23 10 26 9 Jan 1943 14 15 7 13 11 25 29 1K 31 16 20 4 21 22 17 Feb 1943 21 10 16 28 22 15 12 20 7 2 17 26 4* 18* 13* Mar 1943 15 28 13 10 25K 26 27 7 1K 18 29 23 16 30 20 Apr 1943 24 23 14 13 9 12 19 18K 28A 8A 11 3 26 6 5 May 1943 8 9 22 21 31 20 6 10 7 11A 1 18 24 28 15 Jun 1943 17 18 16 30 15 4 3 26 5 2A 8 24 9 21 20 Jul 1943 25 1 14 29 28 24 2 23A 15A 26A 5 6 9 4 10 Aug 1943 22 27 11 12A 10A 23A 6A 21A 7A 25A 31 30 8 9 13 Sep 1943 24A 20A 7A 18A 17A 6A 16A 19A 25A 23A 30 29 3 28 9 Oct 1943 15 14 16 6 13A 18A 21A 5A 19A 23A 26 9 1 2 28 Nov 1943 17 11 15 13 4 3 14 12 2 30A 19 25 27 20 23 Dec 1943 6 11 12 7 28 30 8 13K 27 15A 19 16 17 20 3 Jan 1944 3 30 7 8 25 6 24K 29 4 9 13 11 14 12 15 Feb 1944 3 27 26 25 19 18 6 24 23 1 14 7 8 15 10 Mar 1944 17 24 3 1 15K 21A 20A 23A 16A 25A 27 26 10 19 7 Apr 1944 23 13 22 14 19 20 21 18K 25A 12A 2 16 6 10 5 May 1944 20 16 13 21 18 19 14 17 22 10 1 2 29 6 4 Jun 1944 8 12 3 7 25 6 10 13 19 2 22 15* 26* 21* 23* Jul 1944 24 25 26 27 12 8 28 29 23 11 9* 20* 15* 21* 19* Aug 1944 25 21 29 26 20 22 7 17 16 15 3 28 18 2* 31* Sep 1944 19 17 15 16 6 9 7K 28 13K 10A 30 2 24 21* 23* Oct 1944 8 19 29 9 21 5 30 22 20K 10K 15 11 14 1 3* Nov 1944 13 25 24 27 17 14 21 22 28 15 5 20 6* 4* 10* Dec 1944 7 24 25 12 11 8 10 23 9K 4K 16 17 27 18* 30* Jan 1945 24 25 11 23 14 22 31 8 27 21 29 15 10 17* 16* Feb 1945 21 13 20 1 4 19 14K 23K 24 7A 15 16 26 27* 5* Mar 1945 23 22 30 31 4 19 10 2K 1 9K 15 26 28 12 11 Apr 1945 28 26 9 27 21 17 10 18 3K 29 1 11 12 14 6 May 1945 7 15 22 8 6 5 28 4 17 26K 11 30* 25* 3* 12* Jun 1945 22 29 4 2 1 21 15 24 26 16 6 8* 7* 10* 27* Jul 1945 27 20 15 21 10 22 11 13 25 26 1 6 30* 5* 8* Aug 1945 20 10 19 18 30 25 26 9 24 31 28 2* 14* 23* 13* Sep 1945 24 23 15 14 10 3 8 7 1K 29 18 17 4* 30* 12* Oct 1945 11 10 4 3 26 23 6 31 21 15 24 25 28 12 16* Nov 1945 26 6 24 19 7 1 2 30 27 20 9 11* 12* 16* 10* Dec 1945 4 22 1 3 11 12 2K 18 16 5K 14 27 28 20 26 Jan 1946 14 9 21 20 13 15 28 8 27 10 3 4 24 11 26* Feb 1946 27 1 28 18 16A 17A 26A 11A 12A 2A 8 7 21 14 19 Mar 1946 16 12 3 8 19 13 14 30A 18A 15A 28 25 24 10 26 Apr 1946 21 11 19 20 30 4A 17K 27A 3A 18A 23 24 15 9 14 May 1946 19 27 14 15 30 3A 5A 1A 16A 29A 9 22 11 6 23 Jun 1946 3 24 23K 2 1 30 4K 15A 5A 10A 29 7 19 8 12 Jul 1946 5 1 24 13 4K 6 20 12 31A 2A 27 29 26 7 18 Aug 1946 29 22 23 4 26 21 3 28 5 2 14 31 11 15 7 Sep 1946 1 25 15 6K 26A 3A 14A 13A 2A 8A 22 23 18 28 19 Oct 1946 18 17 8 30 22 13K 24 14 15 21 27 26 9 20 1 Nov 1946 29 27 30 28 14 3 8 4 18 17A 1 21 24 6 25 Dec 1946 14 30 15 16 20K 31 24 9 4 1K 19 12* 27* 11* 22* Jan 1947 11 12 10 13 9 14 15 20 23 31 25 16 26 5 6 Feb 1947 23 22 21 2 14 15 5 13 12 11K 16 17 8 19 9 Mar 1947 11K 1 10 6 21A 5A 19A 20A 25A 18A 3 8 28 2 4 Apr 1947 24 22 23 21A 1A 2A 25A 7A 5A 13A 17 18 9 20 19 May 1947 9 8 2 10 30 4 7K 3 20A 11A 24 16 15 23 14 Jun 1947 2 29 16 27K 4 12A 20A 11A 21A 3A 14 17 5 1 25 Jul 1947 4 5 30 16K 14 3A 15A 28A 31A 6A 18 17 20 19 23 Aug 1947 5 9K 7A 10A 8A 30A 3A 4A 28A 11A 22 18 17 23 16 Sep 1947 10 9K 29A 2A 1A 28A 30A 27A 26A 11A 25 24 3 15 14 Oct 1947 28 27 26 29 30 5 25A 4A 31A 6A 2 10 9 12 15 Nov 1947 6 5 7 26 28 3 22 17A 30A 27A 9 11 10 12 19* Dec 1947 21 31 3 30 17 20 25 16K 24K 22A 6 9 12 13* 5* Jan 1948 4 26 14 24 25 28 15 13 16K 27A 3 8 17 2* 7* Feb 1948 21 1K 26 9 22 20 25K 11A 12A 8A 3 16 15 23 18 Mar 1948 25 24 23 29 28 18 8K 11A 7A 9A 15 1 14 13 2 Apr 1948 8 9 5 19 17 16 11A 23A 4A 10A 22 6 1 21 29* May 1948 19 20 28 26A 5A 14A 27A 31A 18A 17A 16 15 21 7 9 Jun 1948 16 15 29 28 14 4 30 11K 6 23 1 21 26 19* 22* Jul 1948 19 24 23 20 18 27 25 22 2 11 31 4 29* 30* 14* Aug 1948 16 26 27 17 18 5A 25A 15A 6A 3A 8 10 9 12 20 Sep 1948 28 27K 6 20 5A 14A 13A 10A 21A 17A 1 25 29 2 24 Oct 1948 6 9 7K 8 16A 30A 29A 28A 31A 13A 19 18 21 1 15 Nov 1948 30 4 12 5 6K 29K 14 11K 10A 13A 2 20 21 25 22 Dec 1948 1 12 28 4 5K 23A 17A 2A 9A 20A 25 14 31 21 6 Jan 1949 30 5 4 3 15 31 14A 17A 29A 28A 25 26 2 24 18 Feb 1949 9 1 8 25 2 10 28K 19A 26A 5A 22 17 4 24 21 Mar 1949 27 6 11 10 31 7 8A 24A 4A 12A 22 23 14 18 17 Apr 1949 20 6 21 22 30K 4 2K 1 5 19 8 10 11 13 12 May 1949 29 18 20 1 19K 28K 26 27K 24A 21A 12 13 31 4 30 Jun 1949 10 21 23 11 8 20 14K 24A 16A 9A 5 4 12 6 13 Jul 1949 15 4 27 28 10 2 6 5 3 11 16* 23* 19* 13* 17* Aug 1949 25 24 23 12 11 26 1 22A 31A 16A 4 3 14 8 15 Sep 1949 19 20 21 18 10 23 22 29 7 17A 3 12 25 27 2 Oct 1949 3 25 26K 18A 30A 12A 2A 10A 1A 31A 15 14 7 16 8 Nov 1949 8 17 26 7 25 22 28 24K 23A 9A 20 30 2 19 29 Dec 1949 12 11 13 18 7 2 17 8 10 19 9 31* 4* 24* 14*