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Geomagnetic activity in April 1999
Mean Ap12.2No. 568 of 1138
G1+ days4
G3+ days1
Max Ap4717 Apr 1999
Daily Ap
Daily max Kp
| Date | Max Kp | Ap | Level |
|---|---|---|---|
| 16 Apr 1999 | 5o | 18 | G1 |
| 17 Apr 1999 | 7+ | 47 | G3 |
| 28 Apr 1999 | 5- | 19 | G1 |
| 29 Apr 1999 | 5- | 24 | G1 |
Same month a year earlier
| Month | Mean Ap | G1+ | G3+ |
|---|---|---|---|
| April 1998 | 9.8 | 4 | 0 |
| April 1999 | 12.2 | 4 | 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 12.2 in April 1999, No. 568 of 1138 months since 1932; 4 days reached G1 or higher.