NEXRAD (Next-Generation Radar) is the network of about 160 high-powered Doppler radar stations operated by the National Weather Service that supplies the radar data behind nearly every rain map, weather app, and severe storm warning in the United States.

A Nationwide Web of Radar Towers

Each NEXRAD station, officially designated WSR-88D, sits inside the large white dome you may have spotted near an airport or Weather Service office. The stations are spaced across the country so their coverage areas overlap, giving forecasters a near-continuous view of precipitation from coast to coast, though coverage does thin out over parts of the mountain West and offshore.

What Each Station Actually Sends Out

Every NEXRAD site continuously sweeps the sky at multiple angles, sending back both reflectivity data (how heavy precipitation is) and velocity data (wind direction and rotation), the same two data types described in our guide to how Doppler radar works. That raw data feeds directly into the National Weather Service’s warning system and is also what most third-party weather apps and websites display, including a live rain radar map.

Why Some Areas See Better Radar Coverage Than Others

Because the radar beam curves slightly and rises with distance from each tower, locations near a NEXRAD station typically get a clearer, lower-altitude view of precipitation than locations sitting between two distant stations. Mountainous terrain can block the beam entirely in some valleys. Our article on radar blind spots goes into more detail on where and why coverage gaps happen.

In Conclusion

The next time you check a rain map, you’re looking at data gathered by one of roughly 160 government-operated radar towers scanning the sky around the clock. NEXRAD is the quiet infrastructure behind almost every weather warning you’ve ever received.