Sioux City (IA) Temperature by Month

The average annual maximum temperature in Sioux City, Iowa, United States of America is 16°C (61°F), with daytime highs ranging from -1°C (30°F) in January to 30°C (86°F) in July. This page covers monthly averages, day-night differences, and how Sioux City compares to cities worldwide.

Visitors to Sioux City can expect significant temperature changes throughout the year. Nighttime temperatures also vary widely, ranging from 17°C (63°F) in July to -13°C (9°F) in January.

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

Temperatures tend to bottom out between 4 AM and 6 AM, then climb to their daily peak around 3 PM.

The chart below shows the average temperature throughout the year:

Sioux City's average annual maximum temperature is 16°C (61°F). To put that in context, here's how it compares to a few well-known destinations:

Lisbon, Portugal averages 21°C (70°F) annually, warm summers, mild winters, and rain mainly in the cooler months.

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

Buenos Aires, Argentina averages 23°C (73°F) a year, with hot summers and mild winters, and seasons reversed compared to Europe.

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.

For cities and regions with significant elevation, altitude is one of the biggest factors shaping local temperatures. As a rule of thumb, temperatures fall by around 6°C for every 1,000 metres gained, so a city at 2,000 metres will typically be around 12°C cooler than a city at sea level in the same region. Higher ground also tends to see more dramatic day-to-night temperature swings, since thinner air loses heat faster after sunset.

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