Aurora & Space WeatherHome › Geomagnetic history › 1998
Geomagnetic activity in September 1998
Mean Ap12.7No. 530 of 1138
G1+ days3
G3+ days1
Max Ap11725 Sep 1998
Daily Ap
Daily max Kp
| Date | Max Kp | Ap | Level |
|---|---|---|---|
| 18 Sep 1998 | 5+ | 25 | G1 |
| 24 Sep 1998 | 6o | 28 | G2 |
| 25 Sep 1998 | 8+ | 117 | G4 |
Same month a year earlier
| Month | Mean Ap | G1+ | G3+ |
|---|---|---|---|
| September 1997 | 9.8 | 5 | 0 |
| September 1998 | 12.7 | 3 | 1 |
Dates and time slots are UTC. Kp is the 3-hourly planetary geomagnetic index (0–9); Ap is the daily average disturbance. G1–G5 follow the NOAA storm scale (Kp 5- and above counted as G1). Aurora visibility also depends on weather and location. The latest values are preliminary.
About this page
Mean Ap 12.7 in September 1998, No. 530 of 1138 months since 1932; 3 days reached G1 or higher.