G5extreme
The geomagnetic storm of 4 – 5 July 1941
On 4 – 5 July 1941 the Kp index reached 9: a G5 (extreme) storm, with 30 hours at Kp 5 or more. At its peak the lights could be seen from 743,498 places in the atlas, down to about 43° magnetic latitude.
Kp 9Peak Kp · 5 July 1941 12:00 UT
30Hours at Kp 5 or more
400Largest ap
Solar cycle 17Year 8 of solar cycle 17
Kp every three hours
56789
3 Jul4 Jul5 Jul6 Jul
Where the lights could be seen
At Kp 9 the lights reach 743,498 places of the atlas on the horizon and 454,586 overhead, down to about 43° magnetic latitude.
The largest towns that could see them
MoscowRussia · 13.3MNew York CityUnited States · 8.8MLondonUnited Kingdom · 8.8MSaint PetersburgRussia · 5.65MSydneyAustralia · 5.45MMelbourneAustralia · 5.35MBerlinGermany · 3.7MKyivUkraine · 2.95MTorontoCanada · 2.79MBrooklynUnited States · 2.74MChicagoUnited States · 2.73MQueensUnited States · 2.41MParisFrance · 2.1MPerthAustralia · 2.04MViennaAustria · 2.03MMinskBelarus · 2MMontrealCanada · 1.9MHamburgGermany · 1.87MWarsawPoland · 1.86MManhattanUnited States · 1.69MNovosibirskRussia · 1.64MPhiladelphiaUnited States · 1.6MUlaanbaatarMongolia · 1.52MMunichGermany · 1.51M