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Geomagnetic activity in September 1990
Mean Ap13.6No. 457 of 1138
G1+ days6
G3+ days1
Max Ap261 Sep 1990
Daily Ap
Daily max Kp
| Date | Max Kp | Ap | Level |
|---|---|---|---|
| 1 Sep 1990 | 7- | 26 | G3 |
| 11 Sep 1990 | 5- | 25 | G1 |
| 13 Sep 1990 | 5- | 19 | G1 |
| 15 Sep 1990 | 5- | 22 | G1 |
| 16 Sep 1990 | 5o | 23 | G1 |
| 20 Sep 1990 | 5+ | 16 | G1 |
Same month a year earlier
| Month | Mean Ap | G1+ | G3+ |
|---|---|---|---|
| September 1989 | 17.1 | 9 | 3 |
| September 1990 | 13.6 | 6 | 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 13.6 in September 1990, No. 457 of 1138 months since 1932; 6 days reached G1 or higher.