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Geomagnetic activity in December 1999
Mean Ap10.4No. 715 of 1138
G1+ days3
G3+ days0
Max Ap3631 Dec 1999
Daily Ap
Daily max Kp
| Date | Max Kp | Ap | Level |
|---|---|---|---|
| 4 Dec 1999 | 5o | 30 | G1 |
| 13 Dec 1999 | 6- | 26 | G2 |
| 31 Dec 1999 | 6- | 36 | G2 |
Same month a year earlier
| Month | Mean Ap | G1+ | G3+ |
|---|---|---|---|
| December 1998 | 8.2 | 2 | 0 |
| December 1999 | 10.4 | 3 | 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 10.4 in December 1999, No. 715 of 1138 months since 1932; 3 days reached G1 or higher.