January in Keflavík is the rainiest, the windiest, and the cloudiest month of the year. In January, the weather in Keflavík is typically cold. Average daily high temperature in January is about 4 degrees above zero. On average, Keflavík has 29 rainy and 2 sunny days in January. The rains are usually heavy. January as well as February, March, April, and May is considered the most uncomfortable time to visit Keflavík.