May in Bonners Ferry is the rainiest month of the year. In May, the weather in Bonners Ferry is typically warm. Average daily high temperature in May is about 17 degrees above zero. On average, Bonners Ferry has 15 rainy, 10 sunny, and 6 partly cloudy days in May. The rains are usually heavy. May as well as January, February, March, and April is considered the most uncomfortable time to visit Bonners Ferry.