Jefferson, IA Climate

Climate Insight: Jefferson, IA

Jefferson, Iowa runs an annual average of 48°F, ranging from a mean daily high of 58°F to a mean daily low of 37°F, per NOAA's 1991–2020 climate normals. July is typically the warmest month of the year, while January is the coldest. Drawn from station USC00134228, these thirty-year averages smooth out year-to-year swings into a baseline for what a typical month looks like here.

Rainfall (and snow, where it falls) shapes day-to-day life here as much as temperature does. Jefferson sees about 35.3 inches of precipitation a year, with 31.7 inches typically falling as snow. The frost-free season averages 166 days, which directly shapes the planting calendar and growing potential for the area, with the last spring freeze near April 26 and the first fall freeze near October 9. On the energy side, 7,002 heating degree days and 768 cooling degree days tell the story of how often furnaces and air conditioners run during a normal year.

On PlainClimate's composite comfort index, Jefferson scores 59/100 (Moderate), a blended measure that weighs temperature mildness, precipitation moderation, and extreme-weather frequency against one another. The monthly tables above are the practical planning tool: mild highs and lows land in the shoulder seasons, July-driven heat peaks in summer, and January-driven cold sets in over deep winter. These are thirty-year averages, not a forecast - any single year can run warmer, wetter, drier, or cooler than the normal.