Weather Underground was founded in 1995 in Ann Arbor, where it grew out of the University of Michigan’s online weather database. The name was a winking reference to the radical group that also had its roots in Ann Arbor. Mr. Maxwell said he appreciated Weather Underground’s fanatical devotion to data, and how it drew information from so many thousands of weather stations run by users that he is able to determine “microclimates” of variation that can prove important in getting the most out of a new solar installation.

In other words, as he put it on Facebook, “I liked that Wunderground was indy and for weather geeks and not so much ‘normies.’ ”

For Mr. Tucker, the “Nooooooooooooooooo!” response was a reaction to what he sees as the Weather Channel’s penchant for the commercialization of weather. In a telephone interview, he said: “I’m looking at the site right now, and it’s laden with ads, and promotional things for their shows. I don’t really care about all that stuff. I only care what the weather is.”

Mr. Tucker called the Weather Underground site “simple and somewhat elegant” by comparison.

Paul Baginski, a visiting assistant professor of mathematics at Smith College, said that when he assigned his students to run their hometown temperature data through a series of calculus functions, he pointed them toward Weather Underground instead of Weather.com because it was so much easier to track down historical data on the independent site. “It seemed with every update to their Web site, weather.com added another obstacle” with advertisements and extra tabs and clicks, he said.