In May, the weather in San Cristobal de las Casas is typically warm. Average daily high temperature in May is about 23 degrees above zero. On average, San Cristobal de las Casas has 28 rainy, 2 partly cloudy, and 1 sunny day in May. The rains are usually heavy. May as well as June, July, August, and September is considered the most uncomfortable time to visit San Cristobal de las Casas.