August in Alvin is the hottest month of the year. In August, the weather in Alvin is typically hot. Average daily high temperature in August is about 31 degrees above zero. On average, Alvin has 14 sunny, 11 rainy, and 6 partly cloudy days in August. The rains are usually heavy. August as well as July, September, and December is considered the most uncomfortable time to visit Alvin.