Geomagnetic Storms of 1999
44 geomagnetic storms of G1 or more began in 1999: 23 G1, 15 G2, 3 G3, 3 G4, 0 G5. The strongest began October 22, 1999 and reached Kp 8, rank 170 of every storm since 1932.
By month
Every storm of 1999
Times are UT, when the first block at Kp 5 or more began.
| Began (UTC) | Level | Peak Kp | Hours | Highest daily Ap |
|---|---|---|---|---|
| Jan 13, 15:00 | G3 Strong | 7 | 21 | 40 |
| Jan 23, 21:00 | G1 Minor | 5 | 3 | 21 |
| Feb 17, 09:00 | G1 Minor | 5 | 3 | 17 |
| Feb 18, 03:00 | G3 Strong | 7- | 36 | 80 |
| Feb 28, 21:00 | G2 Moderate | 6- | 30 | 41 |
| Mar 4, 06:00 | G1 Minor | 5 | 12 | 30 |
| Mar 10, 00:00 | G2 Moderate | 6+ | 12 | 34 |
| Mar 29, 12:00 | G2 Moderate | 6- | 3 | 28 |
| Apr 16, 21:00 | G3 Strong | 7+ | 15 | 47 |
| May 13, 03:00 | G1 Minor | 5 | 3 | 25 |
| May 18, 18:00 | G1 Minor | 5 | 3 | 27 |
| Jun 27, 12:00 | G2 Moderate | 6 | 21 | 26 |
| Jul 2, 06:00 | G1 Minor | 5 | 3 | 26 |
| Jul 30, 12:00 | G4 Severe | 8- | 12 | 53 |
| Jul 31, 18:00 | G1 Minor | 5+ | 3 | 28 |
| Aug 16, 12:00 | G1 Minor | 5+ | 3 | 29 |
| Aug 17, 06:00 | G1 Minor | 5+ | 3 | 29 |
| Aug 18, 15:00 | G1 Minor | 5 | 3 | 28 |
| Aug 20, 03:00 | G2 Moderate | 6- | 12 | 36 |
| Aug 23, 00:00 | G2 Moderate | 6- | 3 | 31 |
| Aug 24, 12:00 | G2 Moderate | 6- | 3 | 29 |
| Aug 30, 09:00 | G1 Minor | 5 | 3 | 23 |
| Aug 31, 18:00 | G1 Minor | 5 | 3 | 23 |
| Sep 12, 09:00 | G2 Moderate | 6 | 36 | 46 |
| Sep 15, 06:00 | G2 Moderate | 6- | 6 | 27 |
| Sep 16, 03:00 | G2 Moderate | 6 | 6 | 31 |
| Sep 22, 12:00 | G4 Severe | 8 | 18 | 50 |
| Sep 26, 15:00 | G1 Minor | 5+ | 9 | 20 |
| Sep 27, 12:00 | G2 Moderate | 6- | 9 | 43 |
| Sep 30, 03:00 | G1 Minor | 5+ | 3 | 26 |
| Oct 10, 15:00 | G2 Moderate | 6- | 3 | 33 |
| Oct 11, 21:00 | G1 Minor | 5+ | 24 | 46 |
| Oct 14, 15:00 | G1 Minor | 5 | 15 | 31 |
| Oct 21, 03:00 | G1 Minor | 5 | 3 | 20 |
| Oct 22, 00:00 | G4 Severe | 8 | 21 | 91 |
| Oct 23, 12:00 | G1 Minor | 5+ | 6 | 32 |
| Oct 28, 18:00 | G1 Minor | 5+ | 3 | 21 |
| Nov 7, 12:00 | G1 Minor | 5 | 6 | 31 |
| Nov 13, 12:00 | G2 Moderate | 6+ | 12 | 43 |
| Nov 24, 09:00 | G1 Minor | 5 | 3 | 21 |
| Dec 4, 09:00 | G1 Minor | 5 | 9 | 30 |
| Dec 13, 06:00 | G2 Moderate | 6- | 3 | 26 |
| Dec 31, 00:00 | G2 Moderate | 6- | 3 | 36 |
| Dec 31, 21:00 | G1 Minor | 5+ | 6 | 36 |
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.