Understory Inc., a Somerville startup whose real-time, rooftop sensors detect how weather systems are affecting life on the ground, has received nearly $7.5 million in new funding to grow its network of weather stations and open a new location in Madison, Wis.

The weather startup previously raised $1.9 million in a 2014 funding round led by True Ventures of Palo Alto, Calif. True Ventures, which has previously invested in the wearable fitness tracker FitBit, also invested during Understory’s recent fund-raising, which was led by 4490 Ventures of Madison, Wis., and joined by the agricultural biotech behemoth Monsanto Co.

The company was born in Madison but moved to the Boston area two years ago to join the local startup accelerator Bolt. It’s currently headquartered in the startup incubator Greentown Labs in Somerville.

Chief executive Alex Kubicek said he expects to finalize the location of Understory’s Madison branch within the first half of this year.

The new funding will also go towards installing an additional 250 weather-sensing orbs in cities across the country. 

The proprietary sensors, which are entirely solar-powered, track the weather in real time, pulling in data on a location’s humidity, temperature, wind speed, precipitation, and other weather information. Companies and municipalities can use the data to better understand a storm in retrospect, Kubicek said.

In contrast to traditional weather centers, which collect data using satellites floating high in the Earth’s atmosphere, Understory’s weather-sensing orbs gather information at ground level, which the company says is a more accurate way to track  weather.

“What’s interesting,’’ he said, “is that half a trillion dollars in GDP fluctuates just with the weather, so you see our data touches on multiple markets.’’

Understory currently has 50 sensors in three cities; Somerville, Dallas, and Kansas City. Its largest network of sensors is in Kansas City, where 35 sensors, called weather stations, observe the city’s notoriously dynamic weather and catalog the information in Amazon’s cloud storage system. 

Kubicek declined to say which insurance companies Understory works with.

Kubicek said the new funding will allow Understory to begin building weather stations in new markets such as St. Louis and Denver.  

With a high enough density of sensors installed in a given city, Understory hopes it will eventually be able to use the technology to predict the weather.

Last summer, Understory installed two Boston-area sensors on roofs located 2 miles apart in the northwestern and southeastern corners of Somerville. It was part of a partnership established through the city’s GreenTech program, which has the goal of making the city carbon-neutral by 2050. 

Kubicek said Somerville could potentially use the sensors to optimize installation of solar panels, for example, by measuring which places are exposed to the strongest rays for the longest time.

According to Oliver Sellers-Garcia, director of sustainability and environment for Somerville, the city invested in the sensors to allow eco-conscious entrepreneurs, developers, and scientists open access to its ground-level weather data. He said science teachers at a handful of area schools have begun using the data as a teaching tool.

And in an example of a real-time application for the data, Somerville could use it to determine how best to deploy plows and sanders during a snowstorm.

Amanda Burke can be reached at amanda.burke@globe.com