January in Biarritz is the cloudiest and the coldest month of the year. In January, the weather in Biarritz is typically warm. Average daily high temperature in January is about 10 degrees above zero. On average, Biarritz has 14 rainy, 7 sunny, 6 partly cloudy, and 4 cloudy days in January. The rains are usually heavy. January as well as February, March, November, and December is considered the most uncomfortable time to visit Biarritz.