Weather in Iowa City, month by month

Warmest month: July, 24.3
Coldest month: January, -5.6
Wettest month: June, 130 mm
Year: 2001-2020

Same data, same method, different place.

Your own numbers, worked out on the page.

Across the 2001-2020 normals, the warmest month in Iowa City is July at 24.3 degrees and the coldest is January at -5.6, a swing of 29.9 degrees over the year. Those are monthly averages for the model cell the city sits in, not readings from a weather station in it.

Rain is heaviest in June, about 130 mm, and lightest in January at roughly 29 mm. Over a full year the cell above Iowa City collects around 904 mm.

The months whose average sits between 15 and 24 degrees are May, June, August and September. That band is this page's own definition of mild and is stated so you can disagree with it rather than guess at it.

Humidity peaks in December at 85 percent, and the windiest month is April at 3.9 metres per second. Both are monthly means from the same twenty year series as the temperatures.

Rainfall is not spread evenly: 68 per cent of the year total falls in April, May, June, July, August and September.

3 months average below freezing: January, February and December.

Every figure here comes from one NASA POWER grid cell, at 41.66, -91.53, covering Iowa City on the 2001-2020 climatology. One cell, one period and one provider for every month, which is what makes the twelve rows comparable with each other.

The source publishes a monthly mean and, separately, the highest and lowest values it recorded in twenty years. Those extremes are not a typical afternoon or a typical night, so nothing here is quoted as one. This page does not say what the daytime high usually is, because this source cannot say it.

Normals are not a forecast. They describe what twenty years averaged to, and any single year can sit well outside them. They also describe a model grid cell of roughly fifty kilometres rather than a weather station, so a coastal city and the sea beside it share one figure.