Johnston, IA has a humid continental climate, characterized by four distinct seasons. Summers are hot and humid with temperatures averaging in the 80s, while winters are cold and snowy with temperatures dipping into the 20s. The spring and autumn months are milder with temperatures ranging from the 40s to 70s. Precipitation is abundant year round with moderate amounts of snowfall in winter months and frequent thunderstorms during summer.
Johnston, Iowa gets 36 inches of rain, on average, per year. The US average is 38 inches of rain per year.
Johnston averages 34 inches of snow per year. The US average is 28 inches of snow per year.
On average, there are 199 sunny days per year in Johnston. The US average is 205 sunny days.
Johnston gets some kind of precipitation, on average, 109 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 86 degrees
Winter Low: the January low is 13
Rain: averages 36 inches of rain a year
Snow: averages 34 inches of snow a year