In October, the weather in Mariehamn is typically cold. Average daily high temperature in October is about 9 degrees above zero. On average, Mariehamn has 12 rainy, 8 sunny, 7 cloudy, and 4 partly cloudy days in October. The rains are usually moderate. October as well as January, March, November, and December is considered the most uncomfortable time to visit Mariehamn.