May in Rivera is the cloudiest month of the year. In May, the weather in Rivera is typically warm. Average daily high temperature in May is about 18 degrees above zero. On average, Rivera has 12 partly cloudy, 10 sunny, 7 rainy, and 2 cloudy days in May. The rains are usually heavy. May as well as February, June, July, and September is considered the most uncomfortable time to visit Rivera.