A weather forecaster can answer the question, “Why is the sky blue?” only so many times.

That’s why Tribune-owned WB affiliate WGN-TV in Chicago expanded its Tuesday “Ask Tom Why” segment, in which viewers can submit questions to the station’s popular weather forecaster Tom Skilling, to include environmental topics.

Local stations are increasingly turning to their weather forecasters for coverage of the environment. It’s a beat on the periphery of most news directors’ radar screens, but placing environmental coverage under the umbrella of weather allows a local broadcaster to tackle an important area without investing more resources in staffing.

Hearst-Argyle-owned ABC affiliate WCVB-TV in Boston, for instance, extended the responsibilities of weekend meteorologist JC Monahan earlier this year to include the environmental beat. She now contributes occasional pieces to the evening newscasts on important environmental issues. She has recently reported on the multiyear effort to clean up pollution in Boston’s Charles River, a local town’s effort to distribute barrels to residents to collect rainwater for watering gardens and the impact on trees of road salt, used extensively during this year’s snowy winter.

“These are stories with a scientific background angle, and she has the knowledge to work on them,” News Director Coleen Marren said.

The scientific expertise Ms. Monahan brings to bear as a meteorologist and her background in reporting and producing were key factors in assigning her the new role. The station had been assessing how to increase its environmental coverage, Ms. Marren said. “Frankly, there was a lack of [environmental reporting] at this station and our market,” she said.

“In a big market with lots of daily news, there isn’t always that person to focus on the environment,” she said. That’s why leveraging the expertise and time of a weekend weather forecaster during the weekdays for environmental coverage works well, said Kris Wilson, assistant professor in the school of journalism in the University of Texas at Austin. Weathercasters are one of the top reasons viewers tune in to a station, so raising their profile can’t hurt, he added.

NBC-owned WCMH-TV in Columbus, Ohio, has employed a strategy similar to WCVB’s. General assignment reporter Natalie Walston pursues in-depth and investigative environmental stories and weekend meteorologist Marshall McPeek covers weather-related environmental stories during the week.

Mr. McPeek would cover topics such as the effect of runoff from a chicken farmer’s field or fish kills in a small neighborhood creek, said news director Stan Sanders. “He is looking for stories related to the weather and the environment, so he is looking for that stuff,” said Mr. Sanders.

The combination of Mr. McPeek and Ms. Walston, while neither is dedicated to the beat, helps round out the station’s environmental coverage, Mr. Sanders said. “We are all running at 100 miles an hour, but reporters who have special knowledge or interest in [the] field, we send them that way,” he said.

In Chicago, WGN’s weather icon Tom Skilling stretched his focus about four years ago to encompass reports on the environment and scientific topics during the “Ask Tom Why” segments.

Topics have included the city’s efforts to promote rooftop gardens to cool the air, an experiment by the Illinois Institute of Technology to install a wind turbine near Lake Michigan to learn how much lakefront energy can be harnessed, how fire can be beneficial to a natural area as a follow-up to a wildfire that raced through a nature preserve in an Illinois state park earlier this summer, an environmentally friendly solution using Super Soaker water guns to eradicate gypsy moths that were eating trees, and the use of Doppler radar to track bird migration, Mr. Skilling said.

“In almost every one of these, weather is a component and a consideration,” he said. The “Ask Tom Why” pieces also repeat on the noon show on Wednesdays.

WGN expanded the focus because weather can be a limited topic, said Pam Grimes, who produces the segments. “Going into environmental areas has kept the segment fresh. We’re lucky because we have an hour of news, so we have the time to go into some of these things,” she said.