weather in sebastopol, california fahrenheit
California Weather > Sebastopol Weather. Sebastopol, CA climate is mild during summer when temperatures tend to be in the 60's and cold during winter when temperatures tend to be in the 40's. The warmest month of the year is August with an average maximum temperature of 83.80 degrees Fahrenheit, while the coldest month of the year is December with an average minimum temperature of 34.30 degrees Fahrenheit.