Complex sentence: During the Great Blizzard of 1899 the city reached, the only recorded sub-zero Fahrenheit reading in Florida and actually colder than the record low in Ketchikan, Alaska and Tromso, Norway.
Split into simpler sentences: During the Great Blizzard of 1899 the city reached, which was Florida's only recorded reading below. At the time, Tallahassee's record low was colder than the record low in either Ketchikan, Alaska, or Tromso, Norway.