Weather and climate in Iowa: Continental climate characteristics. Cold, snowy winters. Hot, humid summers. Tornado risk during spring. Frequent thunderstorms. Annual flooding concerns. Variable seasonal temperatures. Ice storms in winter. Spring rainfall peaks. Winds from west-northwest.
Continental climate characteristics
Iowa has a humid continental climate, characterized by hot and humid summers with daytime temperatures averaging 74°F (23°C) in July, and cold winters with temperatures ranging from 14°F (-10°C) in the northwest to 22°F (-6°C) in the southeast. The state experiences wet springs, frequent thunderstorms, and light but common snowfall in winters. For more detailed information about Iowa's climate, visit the Iowa Climate Report.
Cold, snowy winters
Iowa experiences cold winters, with January temperatures averaging around 14°F (-10°C) in the northwest and the low 20s°F (about -6°C) in the southeast. Snowfall is relatively light, although heavy snowfalls can occasionally occur in late autumn and early spring. Interestingly, snow cover seldom remains throughout the winter months, providing a dynamic experience of weather variations. For more detailed insights and information, you can visit the Britannica website, an excellent resource for understanding Iowa's climatic conditions.
Hot, humid summers
Iowa experiences hot and humid summers, with relative humidity ranking seventh highest in the country at 72.4%. The humidity is driven by warm air's capacity to hold moisture and saturated soil evaporation. To a lesser extent, this is influenced by transpiration from crops like corn and soybeans. For more detailed insights into these weather patterns, visit the article on Humidity in Iowa.
Tornado risk during spring
Iowa's spring season, particularly April and May, has experienced a significant increase in tornado activity in 2024, with 98 tornadoes recorded in these months. This surge has broken historical records and highlights the state's vulnerability to severe weather events during this time. For more detailed insights, visit the Iowa Weather website, which provides comprehensive coverage and analysis of this unprecedented tornado season.
Frequent thunderstorms
Iowa experiences frequent thunderstorms, particularly during the spring and summer, with an average of 37 tornadoes and at least 50 days of severe thunderstorms. These storms are often part of larger systems that can bring intense precipitation, hail, and strong winds, contributing to the state's unpredictable spring weather.
Annual flooding concerns
Iowa faces significant annual flooding concerns, particularly due to spring flooding caused by rapid snowmelt and heavy rainfall, leading to record-breaking floods, extensive damage, and health risks from contaminated water. Climate change is expected to exacerbate these issues with increased precipitation and more frequent extreme events. To learn more about the initiatives and research addressing these challenges, visit the Focus on Flooding in Iowa page. Stakeholders are working tirelessly to mitigate the impacts of flooding and protect communities from the ongoing threats posed by changing weather patterns.
Variable seasonal temperatures
Iowa's climate is characterized by variable seasonal temperatures, with average annual temperatures increasing by 1.0°F between 1979 and 2021, particularly in fall (1.8°F increase) and winter, where there has been a rapid increase in minimum temperatures. Interestingly, summer temperatures have not warmed substantially. It is important to note that winter minimum temperatures have increased at the most rapid rate, and the growing season has lengthened due to later first frosts and earlier onset of frost-free conditions. For a more comprehensive analysis on this topic, you can refer to the study on Climate Change Impacts on Iowa Agriculture.
Ice storms in winter
A major ice storm recently affected Iowa and Eastern Nebraska, creating treacherous driving conditions and prompting temporary closures of Interstate 80, though warmer air is expected to melt the ice in most areas by Saturday afternoon. This event is part of a predicted colder and snowier winter for the region, influenced by a weak La Nina pattern.
Spring rainfall peaks
Spring rainfall in Iowa has been above average since 1990, with the state's planting season from April to June being particularly wet in recent years, averaging about 2.8 inches above the long-term average of 12 inches since 2008. Increases in winter and spring precipitation are projected, posing a continued risk of spring planting delays and flooding. More detailed climate data and projections can be explored at the State Summaries website.
Winds from west-northwest
In Iowa, winds from the west-northwest are among the dominant wind directions, as indicated by wind roses that show the frequencies of wind direction and speed. These plots, generated by the Iowa Environmental Mesonet, help identify the prevailing wind patterns throughout the year.