Geomagnetic Storms of 1991
69 geomagnetic storms of G1 or more began in 1991: 23 G1, 24 G2, 12 G3, 6 G4, 4 G5. The strongest began March 24, 1991 and reached Kp 9-, rank 27 of every storm since 1932.
By month
Every storm of 1991
Times are UT, when the first block at Kp 5 or more began.
| Began (UTC) | Level | Peak Kp | Hours | Highest daily Ap |
|---|---|---|---|---|
| Jan 12, 06:00 | G1 Minor | 5 | 3 | 19 |
| Feb 1, 18:00 | G2 Moderate | 6- | 9 | 28 |
| Mar 6, 18:00 | G1 Minor | 5 | 3 | 24 |
| Mar 10, 00:00 | G2 Moderate | 6- | 6 | 21 |
| Mar 13, 00:00 | G2 Moderate | 6+ | 9 | 27 |
| Mar 21, 12:00 | G3 Strong | 7- | 3 | 27 |
| Mar 24, 03:00 | G5 Extreme | 9- | 66 | 161 |
| Apr 3, 06:00 | G1 Minor | 5+ | 9 | 37 |
| Apr 4, 09:00 | G3 Strong | 7- | 12 | 50 |
| Apr 27, 03:00 | G1 Minor | 5+ | 3 | 24 |
| Apr 28, 12:00 | G3 Strong | 7- | 42 | 59 |
| May 2, 12:00 | G2 Moderate | 6 | 9 | 45 |
| May 13, 09:00 | G1 Minor | 5 | 6 | 27 |
| May 14, 09:00 | G2 Moderate | 6- | 9 | 33 |
| May 16, 18:00 | G2 Moderate | 6 | 18 | 35 |
| May 24, 12:00 | G2 Moderate | 6- | 21 | 35 |
| May 28, 00:00 | G1 Minor | 5 | 3 | 31 |
| May 28, 21:00 | G1 Minor | 5+ | 6 | 31 |
| May 31, 09:00 | G3 Strong | 7+ | 63 | 74 |
| Jun 4, 15:00 | G5 Extreme | 9- | 45 | 197 |
| Jun 7, 06:00 | G1 Minor | 5+ | 3 | 27 |
| Jun 8, 15:00 | G4 Severe | 8- | 126 | 120 |
| Jun 17, 09:00 | G3 Strong | 7+ | 15 | 67 |
| Jun 23, 09:00 | G2 Moderate | 6 | 21 | 47 |
| Jul 8, 15:00 | G4 Severe | 8 | 36 | 117 |
| Jul 11, 09:00 | G1 Minor | 5 | 3 | 21 |
| Jul 12, 09:00 | G2 Moderate | 6- | 3 | 28 |
| Jul 13, 03:00 | G5 Extreme | 9- | 42 | 134 |
| Jul 16, 15:00 | G2 Moderate | 6- | 18 | 41 |
| Jul 17, 21:00 | G1 Minor | 5+ | 3 | 41 |
| Jul 19, 12:00 | G2 Moderate | 6+ | 21 | 40 |
| Jul 21, 03:00 | G2 Moderate | 6- | 3 | 32 |
| Aug 1, 15:00 | G2 Moderate | 6+ | 27 | 52 |
| Aug 3, 12:00 | G2 Moderate | 6+ | 42 | 44 |
| Aug 5, 21:00 | G2 Moderate | 6 | 9 | 32 |
| Aug 7, 03:00 | G1 Minor | 5+ | 3 | 16 |
| Aug 12, 12:00 | G3 Strong | 7+ | 9 | 64 |
| Aug 14, 21:00 | G1 Minor | 5+ | 9 | 36 |
| Aug 18, 18:00 | G4 Severe | 8- | 21 | 74 |
| Aug 20, 09:00 | G4 Severe | 8- | 24 | 67 |
| Aug 22, 00:00 | G3 Strong | 7 | 9 | 48 |
| Aug 27, 15:00 | G3 Strong | 7- | 9 | 37 |
| Aug 30, 12:00 | G2 Moderate | 6+ | 42 | 52 |
| Sep 1, 18:00 | G2 Moderate | 6 | 15 | 47 |
| Sep 8, 18:00 | G1 Minor | 5 | 3 | 22 |
| Sep 9, 09:00 | G3 Strong | 7 | 24 | 49 |
| Sep 25, 12:00 | G2 Moderate | 6+ | 15 | 50 |
| Sep 27, 00:00 | G2 Moderate | 6- | 45 | 48 |
| Oct 1, 06:00 | G3 Strong | 7+ | 36 | 67 |
| Oct 4, 18:00 | G2 Moderate | 6 | 6 | 35 |
| Oct 6, 21:00 | G2 Moderate | 6- | 9 | 33 |
| Oct 8, 18:00 | G3 Strong | 7- | 3 | 41 |
| Oct 10, 03:00 | G1 Minor | 5+ | 3 | 30 |
| Oct 21, 15:00 | G1 Minor | 5 | 3 | 28 |
| Oct 23, 21:00 | G1 Minor | 5+ | 3 | 22 |
| Oct 25, 15:00 | G1 Minor | 5+ | 6 | 38 |
| Oct 26, 12:00 | G4 Severe | 8+ | 84 | 128 |
| Oct 30, 12:00 | G4 Severe | 8+ | 66 | 109 |
| Nov 4, 09:00 | G2 Moderate | 6 | 18 | 38 |
| Nov 6, 03:00 | G1 Minor | 5 | 3 | 19 |
| Nov 8, 12:00 | G5 Extreme | 9- | 33 | 119 |
| Nov 11, 18:00 | G1 Minor | 5 | 3 | 21 |
| Nov 15, 09:00 | G1 Minor | 5 | 6 | 30 |
| Nov 18, 21:00 | G2 Moderate | 6+ | 24 | 56 |
| Nov 21, 06:00 | G3 Strong | 7- | 33 | 65 |
| Nov 23, 06:00 | G1 Minor | 5 | 6 | 33 |
| Dec 17, 00:00 | G1 Minor | 5+ | 6 | 35 |
| Dec 27, 21:00 | G2 Moderate | 6+ | 3 | 36 |
| Dec 29, 21:00 | G1 Minor | 5+ | 3 | 29 |
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.