The freshly redesigned eighth floor of the Weather Channel’s headquarters feels like some sort of breach in the time-space continuum. This is a 30-year-old TV network in Atlanta, yet the atmosphere is pure Silicon Valley: an open floor plan with no cubicles in sight; employees in their twenties huddled around whiteboards, gripping green markers; even a well-used Foosball table. The young vibe “helps with recruiting and morale,” says Cameron Clayton, president of the company’s digital division. “The goal is to be more collaborative, like a startup.”

TWC’s office overhaul comes at a crucial time for the Weather Channel brand, which is itself in the middle of a reboot. According to Nielsen, the network averaged a five-year low of 211,000 daily viewers in 2013, which is down from 273,000 the previous year. Partly to blame was the year’s unusual dearth of catastrophic U.S. weather events, which typically translate into major ratings. But it isn’t just a lack of hurricanes: TWC is facing a major migration to mobile devices, which are fast replacing TV as the primary source of weather information. Over the past year, according to analytics firm Distimo, the total number of weather apps for iPhone and Android doubled to nearly 10,000.

From left: Dark Sky, SkyMotion, WeatherSphere, and the Weather Channel’s apps are among

thousands that are increasingly competing for customers.

Thanks largely to its brand recognition, TWC’s mobile app is by far the category’s most popular, boasting around 100 million users. But an eager crop of startups, including apps such as Dark Sky, SkyMotion, and WeatherSphere, are beginning to eat away at TWC’s dominance. They’re also changing users’ expec­tations about what a weather forecast should be. Nowcasting–highly accurate short-term weather prediction for a specific location–is finding favor among weather watchers who’ve grown weary of semi-reliable five-day forecasts. While TWC’s app can present conditions in 15-minute intervals, Dark Sky, for example, predicts to the minute, often with startling precision, when it’s going to start raining or snowing within the next hour. SkyMotion does the same for the upcoming two hours. And WeatherSphere’s product, RadarCast, can navigate drivers around oncoming storms.

Now TWC finds itself looking over its shoulder at these growing competitors. “We do pay attention,” says Clayton. “The Weather Channel is perceived as the 800-pound gorilla in the [room]. We’ve allowed some of those apps to occur. We haven’t defended our space as well as I would like.”

Adam Grossman started Dark Sky for a simple reason: ‘I just got tired of getting wet.’

Adam Grossman started Dark Sky for a simple reason: “I just got tired of getting wet.” The 32-year-old web developer, who has a physics degree and no background in meteorology, was sure there had to be a better way to predict imminent weather. Companies like TWC and AccuWeather have typically relied on methods that can delay forecasts, such as having meteorologists interpret data for longer-term predictions. But Grossman envisioned a method that made instant use of available information in order to create something more immediately useful than the seven-day, or even hourly, forecast. He thought he could tap National Weather Service radar, satellites, personal weather stations, and his own statistical “secret sauce” (a program that virtually erases distortions such as birds and fog from weather radar) to improve short-term forecasting. After raising $40,000 on Kickstarter, Grossman and a partner, Jack Turner (who has since left the company), debuted Dark Sky in early 2012. The $3.99 app has since been downloaded about 400,000 times.

Large companies are starting to notice the success of the Dark Sky model. Last fall, agriculture giant Monsanto spent $1 billion to acquire the Climate Corp., which provides hyperlocal weather data to farmers. That was followed by AccuWeather’s November purchase of the Dark Sky–like SkyMotion. “Most of the good weather apps aren’t made by the big guys anymore,” says Grossman.