Aurora & Space WeatherHome › Geomagnetic history › 1987
Geomagnetic activity in September 1987
Mean Ap19.3No. 170 of 1138
G1+ days14
G3+ days0
Max Ap4625 Sep 1987
Daily Ap
Daily max Kp
| Date | Max Kp | Ap | Level |
|---|---|---|---|
| 1 Sep 1987 | 5+ | 34 | G1 |
| 10 Sep 1987 | 6+ | 38 | G2 |
| 11 Sep 1987 | 5+ | 40 | G1 |
| 13 Sep 1987 | 5o | 23 | G1 |
| 14 Sep 1987 | 5o | 26 | G1 |
| 15 Sep 1987 | 5o | 29 | G1 |
| 16 Sep 1987 | 5- | 19 | G1 |
| 22 Sep 1987 | 6+ | 29 | G2 |
| 23 Sep 1987 | 6- | 17 | G2 |
| 25 Sep 1987 | 6o | 46 | G2 |
| 26 Sep 1987 | 5- | 20 | G1 |
| 28 Sep 1987 | 5o | 22 | G1 |
| 29 Sep 1987 | 5+ | 30 | G1 |
| 30 Sep 1987 | 6o | 43 | G2 |
Same month a year earlier
| Month | Mean Ap | G1+ | G3+ |
|---|---|---|---|
| September 1986 | 16.6 | 9 | 1 |
| September 1987 | 19.3 | 14 | 0 |
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 19.3 in September 1987, No. 170 of 1138 months since 1932; 14 days reached G1 or higher.