January in Omis is the rainiest, the cloudiest, and the coldest month of the year. In January, the weather in Omis is typically cold. Average daily high temperature in January is about 7 degrees above zero. On average, Omis has 13 rainy, 10 sunny, 7 partly cloudy, and 1 cloudy day in January. The rains are usually heavy. January as well as February, March, and December is considered the most uncomfortable time to visit Omis.