When the Northern Light Hits the Sky

Within the auroral zone, the aurora can be seen every clear
winter night. There are other regular variations:

• The aurora is most frequent and intense from 2200 to
  midnight, magnetic time.

• Brilliant auroras often occur at 27-day intervals as
  active areas on the sun's surface face earth during its
  27-day rotation cycle.

• Northern lights are more frequent in late autumn and
  early spring. October, February and March are the best
  months for auroral observations in northern Norway.

• Northern lights activity corresponds closely to sunspot
  activity, which follows an 11-year cycle, but there seems
  to be a one-year delay between sunspot maximum and maximum
  auroral occurrence.

• Northern lights activity is 20-30% less during solar minimum
  than at solar maximum.

Northern lights are observed in Mediterranean countries only
when solar activity is extremely high, maybe tens of years
apart, and on average only once every 100 years.

Northern lights can be observed this
often on the following places during solar maximum:

Andenes, Norway
Almost every dark and clear night

Fairbanks, Alaska
Five to ten times a month

Oslo, Norway
Roughly three nights a month

Northern Scotland, Great Britain
Roughly once a month

US/Canadian border
Two to four times a year

Mexico and Mediterranean countries
Once or twice a decade

South of the Mediterranean countries
Once or twice a century

Equator
Once in two hundred years