May in Arecibo is the rainiest and the cloudiest month of the year. In May, the weather in Arecibo is typically warm. Average daily high temperature in May is about 27 degrees above zero. On average, Arecibo has 20 rainy, 7 sunny, 2 cloudy, and 2 partly cloudy days in May. The rains are usually moderate. May as well as September and November is considered the most uncomfortable time to visit Arecibo.