May in Niamey is the hottest month of the year. In May, the weather in Niamey is typically hot. Average daily high temperature in May is about 40 degrees above zero. On average, Niamey has 18 partly cloudy, 11 sunny, and 2 cloudy days in May. May as well as March, April, June, and July is considered the most uncomfortable time to visit Niamey.