AMES, Iowa — Twenty-five years ago, Iowa State University rolled out the Iowa Environmental Mesonet website. Since then, it has become the central hub for all things weather-related in Iowa with a reach far beyond the state.
What is a mesonet?
Mesonets are networks of weather stations that collect and provide “meso-scale,” generally at the scale of a county, data on temperature, precipitation and soil moisture, according to Dennis Todey, a physical scientist at the Agricultural Research Service’s National Laboratory for Agriculture and the Environment. When the IEM was created, he worked at Iowa State and helped develop it.
“The state needed more comprehensive and accessible weather data for all kinds of reasons,” Todey said. “Eventually a group of stakeholders got involved to make it happen. Today it is recognized as one of the best in the nation.”
Iowa’s mesonet collects and integrates information from eight weather-observing networks, including the National Weather Service, the Federal Aviation Administration, Iowa Department of Transportation weather stations, Iowa State soil moisture data stations on research farms, and volunteers who report readings from special thermometers and rain gauges. The mesonet also uses specialized data from research projects and other sources.
The most-frequented website at Iowa State, the IEM averages 230 million daily website requests from individuals, business and other weather platforms that use its datasets for everything from precision farming apps to local TV weather forecasts.
Daryl Herzmann, a technical project specialist with Iowa State’s Department of Agronomy, runs the site. He started working for the IEM project as an undergraduate research assistant in 2001 and, over the years, has become the IEM’s managing guru.
The Daily Feature
Herzmann’s Daily Feature web column is a popular feature for weather-curious Iowans. It has recently highlighted topics such as “About Those 90°F Dew Points,” which discusses corn sweat, and the “Northern Polk, Southern Story Deluge” of early July. In the winter, readers could track snowfall comparisons and read about the first thunderstorm of the year (Jan. 9, 2026).
Underpinning the Daily Feature are layers of information that provide much more than conversation starters for weather nerds. Its regular users include:
- Ag producers, who use it to inform decision-making about crops and farm management timing.
- USDA officials, who rely on the data to help guide crop insurance programs, and the agency’s predictions on potential crop yields and losses made by the Office of the Chief Economist.
- National Weather Service staff working to track severe weather warnings and conditions leading to droughts and floods.
Ag business resource
Scott Nelson is a research agronomist with Acumen Ag. His Iowa-based business is one of many agricultural retailers who use IEM-based data to help guide clients.
“Increasingly, consulting agronomists are doing crop modeling to help inform precision agriculture. We need good, reliable weather data. The IEM is an important resource for everything from wind speeds to evapotranspiration and precipitation,” Nelson said.
“But there’s a huge amount of information there. One of the biggest benefits of the Iowa mesonet is the interpretation and personal assistance that Daryl provides. He’s widely known as being very responsive and helpful. That’s valuable to many of us.”
Tools for science and teaching
Herzmann helps scientists integrate, process and visualize weather data for yield experiments, pest forecasts and flood predictions, long-term crop modeling and other types of studies.
Brian Hornbuckle, professor of agronomy, is Iowa State’s director of graduate education for agricultural meteorology. He primarily uses the IEM as a teaching tool, encouraging his students to review the Daily Feature and dig into the mesonet’s many products for class projects.
“Daryl takes data that may be freely available, but perhaps hard to find, and makes it easily accessible and useful,” Hornbuckle said.
One well-known project that Herzmann supports is the Daily Erosion Project. The DEP’s director, Richard Cruse, supervises the IEM.
“Daryl’s understanding of meteorology, data processing and product creation for end-users is remarkable,” Cruse said. “It’s impressive how he can envision how to do something and then makes it happen, for example, by combining models and making them work together.”
“His impact also goes well beyond Iowa,” Cruse continued. “When hurricanes devastated roads and bridges in North Carolina two years ago, many depended on that state’s travel dashboard website that was using an IEM-provided map layer based on National Weather Service radar. It successfully serviced daily usage of just under a billion web requests at one point -- a testament to the robust infrastructure Daryl has built.”
“Funding for the IEM has come from various sources over the years, including grants that may not be as available in the future,” Cruse said. “It would be a huge loss to lose this resource that so many rely on,” Cruse said.
Never boring
At this summer’s gathering to toast the IEM’s 25th year, attendees acknowledged the contributions of those who helped establish the IEM, including Todey and Ray Arritt, a former agronomy professor who died six years ago. Herzmann, especially, received accolades for continuing and expanding on their vision. Standing with his family, Herzmann took it in stride.
“I’m lucky. It’s a great job,” he remarked later. “The weather is never boring.”
Contacts
Daryl Herzmann, Department of Agronomy, 515-451-9249, akrherz@iastate.edu
Rick Cruse, Daily Erosion Project, 515-294-7850, rmc@iastate.edu
Brian Hornbuckle, Department of Agronomy, 515-294-9868, bkh@iastate.edu
Ann Y. Robinson, Agriculture and Life Sciences Communications,
515-294-3066, ayr@iastate.edu