January in Biarritz is the coldest month of the year. In January, the weather in Biarritz is typically warm. Average daily high temperature in January is about 11 degrees above zero. On average, Biarritz has 16 rainy, 7 partly cloudy, 6 sunny, and 2 cloudy 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 Biarritz.