January in Joplin is the coldest month of the year. In January, the weather in Joplin is typically cold. Average daily high temperature in January is about 5 degrees above zero. On average, Joplin has 15 sunny, 12 partly cloudy, and 4 rainy days in January. The rains are usually light. January as well as February, March, and December is considered the most uncomfortable time to visit Joplin.