Ballwin, MO has a humid subtropical climate with hot and humid summer months and cold winters. The summers in Ballwin typically have temperatures in the high 80s and low 90s, with occasional heat waves that can push temperatures up near 100 degrees. Average winter temperatures are in the high 30s and low 40s, with occasional days dipping down to below freezing. Snowfall during the winter is usually light, and rainfall is spread out over most of the year, though summer storms often bring heavy rainfall during short periods of time.
Ballwin (zip 63021), Missouri gets 44 inches of rain, on average, per year. The US average is 38 inches of rain per year.
Ballwin (zip 63021) averages 12 inches of snow per year. The US average is 28 inches of snow per year.
On average, there are 202 sunny days per year in Ballwin (zip 63021). The US average is 205 sunny days.
Ballwin (zip 63021) gets some kind of precipitation, on average, 98 days per year. Precipitation is rain, snow, sleet, or hail that falls to the ground. In order for precipitation to be counted you have to get at least .01 inches on the ground to measure.
Weather Highlights
Summer High: the July high is around 88 degrees
Winter Low: the January low is 21
Rain: averages 44 inches of rain a year
Snow: averages 12 inches of snow a year