Aurora towns in Sweden

Of the 74 indexed towns in Sweden, 11 sit at 60 degrees geomagnetic or more, in or poleward of SWPC's 60 to 75 degree band, where no storm is needed; 63 sit between 55 and 60 degrees, where G1 (Kp 5) or less usually brings aurora into view.

On December 15 the median town gets 15.8 hours of civil night. Kiruna has the most at 18.3 hours and Helsingborg the least at 15.3. 16 of these towns lose civil darkness altogether around the June solstice; Kiruna goes longest, 98 nights.

NASA POWER's 2001 to 2020 climatology puts median cloud amount in the dark months at 75%. Landskrona is clearest at 70% and Haninge cloudiest at 78%. These are all-hours averages for 1 degree cells, not forecasts.

Multiplying civil night by the clear share of the sky, October comes out best for 27 of the 74 towns and September for 19. SWPC notes a tendency toward larger storms near the equinoxes, which this score does not include.

The towns fall in 21 first-level regions. Stockholm has 22, Västra Götaland has 18, Skåne has 10, Halland has 4. Regions with at least 5 indexed towns have their own page with three rankings.

• Stockholm22 towns
• Västra Götaland18 towns
• Skåne10 towns
• Halland4 towns
• Jönköping4 towns
• Norrbotten4 towns
• Dalarna3 towns
• Gävleborg3 towns
• Kalmar3 towns
• Örebro3 towns
• Östergötland3 towns
• Södermanland3 towns
• Västernorrland3 towns
• Blekinge2 towns
• Kronoberg2 towns
• Uppsala2 towns
• Värmland2 towns
• Västerbotten2 towns
• Västmanland2 towns
• Gotland1 towns
• Jämtland1 towns