Geomagnetic Storms of 1947
51 geomagnetic storms of G1 or more began in 1947: 18 G1, 18 G2, 8 G3, 6 G4, 1 G5. The strongest began April 17, 1947 and reached Kp 9-, rank 59 of every storm since 1932.
By month
Every storm of 1947
Times are UT, when the first block at Kp 5 or more began.
| Began (UTC) | Level | Peak Kp | Hours | Highest daily Ap |
|---|---|---|---|---|
| Jan 16, 03:00 | G2 Moderate | 6+ | 3 | 36 |
| Jan 16, 18:00 | G1 Minor | 5 | 3 | 36 |
| Jan 24, 06:00 | G2 Moderate | 6- | 3 | 22 |
| Jan 25, 03:00 | G2 Moderate | 6+ | 27 | 61 |
| Feb 8, 21:00 | G1 Minor | 5 | 3 | 27 |
| Feb 16, 09:00 | G2 Moderate | 6+ | 24 | 44 |
| Feb 19, 15:00 | G1 Minor | 5 | 3 | 24 |
| Mar 2, 06:00 | G4 Severe | 8+ | 63 | 128 |
| Mar 8, 06:00 | G4 Severe | 8- | 30 | 91 |
| Mar 14, 15:00 | G1 Minor | 5+ | 3 | 25 |
| Mar 15, 06:00 | G3 Strong | 7+ | 12 | 74 |
| Mar 17, 00:00 | G1 Minor | 5+ | 3 | 24 |
| Mar 22, 03:00 | G1 Minor | 5 | 3 | 21 |
| Mar 23, 15:00 | G2 Moderate | 6+ | 18 | 33 |
| Mar 28, 00:00 | G3 Strong | 7- | 24 | 75 |
| Mar 30, 00:00 | G2 Moderate | 6- | 6 | 35 |
| Apr 8, 21:00 | G2 Moderate | 6- | 15 | 33 |
| Apr 17, 12:00 | G5 Extreme | 9- | 36 | 100 |
| Apr 20, 03:00 | G1 Minor | 5 | 6 | 30 |
| May 15, 21:00 | G1 Minor | 5 | 12 | 36 |
| May 23, 03:00 | G2 Moderate | 6- | 6 | 24 |
| May 24, 06:00 | G4 Severe | 8- | 6 | 52 |
| May 28, 12:00 | G1 Minor | 5 | 3 | 19 |
| May 29, 15:00 | G1 Minor | 5 | 3 | 22 |
| Jun 1, 00:00 | G2 Moderate | 6- | 6 | 27 |
| Jun 5, 06:00 | G2 Moderate | 6 | 3 | 34 |
| Jun 5, 21:00 | G2 Moderate | 6- | 6 | 34 |
| Jun 7, 21:00 | G1 Minor | 5 | 9 | 22 |
| Jun 13, 21:00 | G3 Strong | 7 | 24 | 63 |
| Jun 17, 03:00 | G2 Moderate | 6 | 18 | 40 |
| Jul 17, 15:00 | G4 Severe | 8 | 36 | 80 |
| Jul 20, 15:00 | G1 Minor | 5+ | 3 | 31 |
| Aug 12, 03:00 | G1 Minor | 5 | 3 | 28 |
| Aug 13, 15:00 | G1 Minor | 5+ | 9 | 26 |
| Aug 15, 09:00 | G4 Severe | 8+ | 201 | 71 |
| Aug 25, 09:00 | G1 Minor | 5+ | 3 | 28 |
| Sep 3, 06:00 | G3 Strong | 7+ | 33 | 84 |
| Sep 7, 12:00 | G3 Strong | 7- | 15 | 45 |
| Sep 11, 15:00 | G1 Minor | 5 | 3 | 17 |
| Sep 13, 00:00 | G2 Moderate | 6+ | 72 | 62 |
| Sep 16, 21:00 | G2 Moderate | 6 | 51 | 55 |
| Sep 22, 06:00 | G2 Moderate | 6+ | 33 | 42 |
| Sep 24, 06:00 | G4 Severe | 8- | 39 | 100 |
| Oct 1, 03:00 | G3 Strong | 7- | 51 | 61 |
| Oct 9, 09:00 | G2 Moderate | 6 | 84 | 61 |
| Oct 14, 06:00 | G2 Moderate | 6 | 42 | 47 |
| Oct 16, 15:00 | G1 Minor | 5 | 3 | 23 |
| Oct 19, 18:00 | G2 Moderate | 6+ | 3 | 29 |
| Nov 9, 09:00 | G3 Strong | 7 | 18 | 62 |
| Nov 10, 18:00 | G3 Strong | 7- | 36 | 53 |
| Nov 24, 18:00 | G1 Minor | 5+ | 3 | 13 |
More
Sources
Kp and ap from GFZ Helmholtz Centre for Geosciences, Geomagnetic Observatory Niemegk, licensed CC BY 4.0: Matzka, J., Stolle, C., Yamazaki, Y., Bronkalla, O. and Morschhauser, A., 2021, The geomagnetic Kp index and derived indices of geomagnetic activity, Space Weather, doi:10.1029/2020SW002641; data doi:10.5880/Kp.0001. Storms, levels and aurora reach worked out by WeatherOverTime from those values and NOAA’s space weather scales. Definitive through August 31, 2026; later values are preliminary. Rebuilt 2026-09-24.