Aurora & Space WeatherGeomagnetic activity in 1999
Mean Ap12.5
G1+77days
G3+6days
G50days
G1+ days by month
- January 1999
- February 1999
- March 1999
- April 1999
- May 1999
- June 1999
- July 1999
- August 1999
- September 1999
- October 1999
- November 1999
- December 1999
Nearby years (G1+ days)
125
100
41
43
54
77
83
63
74
158
60
Top 10 days by Ap
| Date | Max Kp | Ap | Level |
|---|---|---|---|
| 22 Oct 1999 | 8o | 91 | G4 |
| 18 Feb 1999 | 7- | 80 | G3 |
| 30 Jul 1999 | 8- | 53 | G4 |
| 22 Sep 1999 | 8o | 50 | G4 |
| 17 Apr 1999 | 7+ | 47 | G3 |
| 13 Sep 1999 | 6o | 46 | G2 |
| 12 Oct 1999 | 5+ | 46 | G1 |
| 27 Sep 1999 | 6- | 43 | G2 |
| 13 Nov 1999 | 6+ | 43 | G2 |
| 1 Mar 1999 | 6- | 41 | G2 |
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
1999 had 77 G1+ storm days (No. 42 of 95 years) and 6 G3+ days.