Hall of storms · #8 / 10
September 18–19, 1941
Peak Kp
Kp 9.0
G5 — top storm class
Peak moment
03:00 UTC
September 19, 1941
Duration
2 days
September 18–19, 1941
At the ceiling
9.0 ×1
1 intervals at Kp 9.0
What it reached
North America & Europe — aurora over wartime blackouts
Open in the archive
September 1941 — the three-hourly Kp values, day by day