How to Use a Rain Radar to Track Incoming Weather
Use the NWS radar viewer’s location search, radar loop, and legend to judge whether precipitation is moving toward your area.
Open the National Weather Service radar viewer and search for your location. Select a radar view, start its loop, and compare the precipitation echoes with the map and legend to see whether they are approaching. The official NWS radar FAQ describes the viewer’s controls and available products.
Before you start
Use a browser with an internet connection. The supplied NWS documentation describes a web-based radar viewer; it does not specify separate app instructions.
Know the place you want to check, such as a town or nearby landmark.
Keep in mind that radar displays echoes measured by radar. It is useful for observing precipitation and movement, but it is not a guarantee of exactly what is happening at your street.
The FAQ describes the viewer’s Version 2.0 updates and was last updated September 6, 2023. The supplied material does not establish newer interface changes, device-specific differences, or which features are free or paid. Follow the labels shown in your viewer if they differ from the descriptions below.
Track precipitation near your location
1. Find your area
Use the map’s location search to find the place you care about. Check that the map is centered on the correct area, then zoom in or out with the map controls. The NWS FAQ lists location search and zoom among the viewer’s main features.
Expected result: Your location is visible on the map, with nearby radar echoes and map features available for context.
2. Choose a radar view
Select a view that shows radar data for your area. The FAQ describes both national radar mosaic and radar station products views, as well as view selection and additional map options. The precise list of products can vary by view, so use the choices presented in the viewer rather than looking for a particular product name that may not be available.
For a general rain check, look for a reflectivity product. The FAQ describes the national mosaic product BREF.QCD as showing echo intensity measured in dBZ, with ground clutter and non-precipitation echoes removed. Scientists use it to detect precipitation and evaluate storm structure. Use the displayed legend to interpret the colors; do not infer a specific rainfall amount from color alone.
Expected result: The map displays a radar layer, and its legend explains the selected product’s scale.
3. Play the radar loop
Use the map’s loop control to view several radar images in sequence. Watch the echoes in relation to your location and surrounding geography. The NOAA overview explains that looking at radar images over time can offer clues about where precipitation is moving and how fast it is falling.
To judge whether rain may be incoming, compare successive frames: note whether the precipitation area is getting closer to your location, moving away, or changing shape. A single frame shows where echoes are at that moment; the loop provides the movement context.
Expected result: You can see a sequence of radar images rather than relying on one snapshot. The viewer also provides map time for the selected product or products, according to the NWS FAQ.
4. Check warnings and map context
Look for warnings displayed on the map. The FAQ says storm-based warnings display by default in the National radar mosaic and Radar station products views. It also says you can use the view options, shown as three vertical dots, to choose to display all warnings on those views.
Use map overlays and the legend when available to orient yourself. The FAQ lists overlays such as counties, rivers, highways, cities, and warnings. These can help you relate the radar image to nearby places, but they do not replace reading the warning details.
Expected result: You can see the selected warning display and identify the areas shown on the map. If you need all warnings rather than the default storm-based display, check the view options.
Example: deciding whether an echo is approaching
Suppose your town is near the center of the map and a band of echoes appears to one side. Play the loop and compare its position across frames. If the band shifts closer to your town, that is a reason to keep monitoring it. If it shifts away, it may be moving away from the area. This is an example of how to read the sequence, not a forecast for a specific place or time.
Troubleshooting and verification
The radar map does not appear
The NWS FAQ notes that the radar application may fail to display and suggests refreshing the browser cache. Its listed shortcuts are Ctrl + F5 on Windows and Linux, and Cmd + Shift + R in Chrome and Firefox on Mac. For Safari on iPhone or iPad, the FAQ lists Settings > Safari > Advanced > Website Data > Edit > weather.gov, then deleting the site data. Deleting website data may affect saved site state, so use that step only if you are comfortable doing so.
If the map still does not display, consult the NWS radar FAQ for the viewer’s help and troubleshooting information. The FAQ also says information about a radar that may be down can be found by selecting that radar and checking its radar selection/customization dropdown under the radar identifier.
The colors or symbols are unclear
Check the legend for the currently selected product. The NWS viewer’s legend is for the selected radar product, so changing products can change what the map’s colors mean. Do not apply an interpretation from one product to another without checking its legend.
The map is centered on the wrong place or looks customized
Search for the location again. If you want to restore the map, the FAQ gives this menu path: map options, then Reset Map. The available option labels may depend on the current viewer interface.
Confirm that tracking is working
You have completed the check when the map shows your intended area, a radar product and its legend are visible, and the loop advances through images with map times. Compare at least two frames to determine whether the precipitation echoes are moving closer to or farther from your location. Recheck warnings and the loop later if conditions are changing.
