Grinnell (IA) Temperature by Month

Grinnell in Iowa, United States of America sees significant seasonal temperature differences, with daytime highs between -2°C (28°F) in January and 29°C (84°F) in July, averaging 15°C (59°F) annually. Explore the full monthly breakdown below.

Depending on the time of the year, temperatures range from comfortable to very cold in Grinnell. At night, minimum temperatures range from 18°C (64°F) in July to -12°C (10°F) in January.

The chart below illustrates the average maximum day and minimum night temperatures in Grinnell by month:

The coldest point of the day usually falls between 4 AM and 6 AM, with temperatures peaking around 3 PM.

The chart below shows the average temperature throughout the year:

Grinnell's average annual maximum temperature is 15°C (59°F). To put that in context, here's how it compares to a few well-known destinations:

Seville, Spain averages 23°C (73°F) a year, one of the warmer cities in Western Europe, with long hot summers.

Toronto, Canada averages 13°C (55°F) annually, with cold snowy winters balanced by genuinely warm summers.

New York City, USA averages 17°C (63°F) a year, with hot humid summers and cold winters that bring regular snowfall.

Melbourne, Australia averages 20°C (68°F) annually, known for unpredictable weather, with four seasons sometimes happening in one day.

Climate temperature data is typically calculated as a 30-year average. This smooths out year-to-year variability and gives a more reliable picture of what a place is actually like, rather than what happened in any single unusual year.

The readings come from a range of sources, land-based weather stations, ocean buoys, ships, and satellites. That data is collected by weather services around the world, then pooled, quality-checked, and averaged to produce the climate records you see here.

Seasonal temperature shifts influence more than just how warm it feels, they also drive changes in rainfall, cloud cover, and wind patterns throughout the year.

Warmer air holds more moisture, which tends to mean heavier or more frequent rain during the warmer months. When temperatures drop in winter, any precipitation that does fall is more likely to come as snow or sleet, though in Grinnell this rarely lasts long on the ground.

For more on Grinnell's weather, including monthly rainfall, sunshine hours, and humidity, visit our Grinnell climate page.