The National Digital Forecast Database (NDFD) Web Services provide a set of gridded weather forecasts for various sensible weather elements in near real-time. These forecasts are generated by a collaboration between the National Weather Service (NWS) field offices and the National Centers for Environmental Prediction (NCEP). The NDFD Web Services offer a seamless, digital mosaic of weather forecasts that can be accessed by users to obtain up-to-date information on a variety of weather conditions.
The NDFD's forecasts are gridded, meaning they cover large geographic areas with weather data at specific intervals, providing high-resolution, geographically distributed forecasts. These forecasts can include temperature, precipitation, wind speed and direction, cloud cover, and other meteorological parameters.
These web services are hosted by the Office of Dissemination’s CloudGIS team, which ensures the forecasts are readily accessible and deliverable over the internet. Users, including meteorologists, developers, and anyone interested in weather data, can query these web services for up-to-date forecasts in a digital format, enabling integration into applications, websites, and other platforms.
NDFD’s Web Services Descriptions:
12-Hour Probability of Precipitation Web Service's data layer is the likelihood, expressed as a percent, of a measurable precipitation event (1/100th of an inch or more) at a grid point during the 12-hour valid period. The 12-hour valid periods begin and end at 0000 and 1200 Coordinated Universal Time (UTC).
Apparent Temperature Web Service: contains data that is the perceived temperature derived from either a combination of temperature and wind (Wind Chill) or temperature and humidity (Heat Index) for the indicated hour. When the temperature at a particular grid point falls to 50 F or less, wind chill will be used for that point for the Apparent Temperature. When the temperature at a grid point rises above 80 F, the heat index will be used for Apparent Temperature. Between 51 and 80 F, the Apparent Temperature will be the ambient air temperature.
Dew Point Temperature Web Service's data is the expected dew point temperature for the indicated hour. Dew point temperature is a measure of atmospheric moisture. It is the temperature to which air must be cooled in order to reach saturation (assuming air pressure and moisture content are constant).
Maximum Temperature Web Service's data is the daytime maximum temperature observed from 7 AM to 7PM LST.
Minimum Temperature Web Service's data is predicted minimum temperature for a specific location at a given time, allowing users to visualize the lowest expected temperatures across a geographical area.
Precipitation Amount Web Service's data is the expected quantity of liquid precipitation accumulated over a six-hourly period. A quantitative precipitation forecast (QPF) will be specified when a measurable (1/100th of an inch or more) precipitation type is forecast for any hour during a QPF valid period. NDFD valid periods for QPF are 6 hours long beginning and ending at 0000, 0600, 1200 and 1800 UTC. QPF includes the liquid equivalent amount for snow and ice.
Relative Humidity Web Service's data is a ratio, expressed as a percent, of the amount of atmospheric moisture present relative to the amount that would be present if the air were saturated. Since the latter amount is dependent on temperature, relative humidity is a function of both moisture content and temperature.
Sky Cover Web Service’s data is the predicted percentage of the sky that will be covered by opaque clouds at a given time, provided by the National Digital Forecast Database (NDFD). It is a forecast of how much of the sky will be obscured by clouds, expressed as a percentage value.
Snow Amount Web Service's data is the expected total accumulation of new snow during a 6-hour period. A snow accumulation grid will be specified whenever a measurable snowfall is forecast for any hour during a valid period. Valid periods for the NDFD begin and end at 0600, 1200, 1800, and 0000 UTC.
Temperature Web Service: contains data that is the expected temperature in degrees Fahrenheit valid for the indicated hour.
Wave Height Web Service's data is the average height (from trough to crest) of the one-third highest waves valid for the top of the designated hour. Wave Height is a combination of wind waves and swell.
Wind Direction Web Service's data is the expected sustained 10-meter wind direction for the indicated hour, using 36 points of a compass.
Wind Gust Web Service's data is the maximum 3-second wind speed forecast to occur within a 2-minute interval at a height of 10 meters. Wind gust forecasts are valid at the top of the indicated hour.
Wind Speed Web Service's data is the expected sustained 10-meter sustained wind speed for the indicated hour.
Wind Speed and Direction Web Service's data is the expected sustained 10-meter wind direction for the indicated hour, using 36 points of a compass. Wind Speed is the expected sustained 10-meter sustained wind speed for the indicated hour. Wind barbs (shown below) are used to denote wind speed and direction.
Update Frequency: The data in these service updates Go to Table.
Link to graphical web page: https://digital.weather.gov
Link to data download (grib2): https://tgftp.nws.noaa.gov/SL.us008001/ST.opnl/DF.gr2/DC.ndfd/
Link to metadata
Questions/Concerns about the service, please contact the DISS GIS team.
Time Information:
These web services are time-enabled, meaning that each individual layer contains time-varying data and can be utilized by clients capable of making map requests that include a time component. These particular services can be queried with or without the use of a time component. If the time parameter is specified in a request, the data or imagery most relevant to the provided time value, if any, will be returned. If the time parameter is not specified in a request, the latest data or imagery valid for the present system time will be returned to the client. If the time parameter is not specified and no data or imagery is available for the present time, no data will be returned.
| Service | Valid Time |
|---|---|
| 12-Hour Probability of Precipitation Web Service | The 12-hour valid periods begin and end at 0000 and 1200 Coordinated Universal Time (UTC). |
| Apparent Temperature Web Service | CONUS displays every hour; OCONUS displays every 3 hours (03Z, 06Z, 09Z, 12Z, etc) |
| Dew Point Temperature Web Service | CONUS displays every hour; OCONUS displays every 3 hours (03Z, 06Z, 09Z, 12Z, etc) |
| Maximum Temperature Web Service | Display 00Z every day |
| Minumum Teperature Web Service | Display at 12Z every day |
| Precipitation Amount Web Service | CONUS/OCONUS (forecast is valid at 00Z, 06Z, 12Z and 18Z) |
| Relative Humidity Web Service | CONUS displays every hour; OCONUS displays every 3 hours (03Z, 06Z, 09Z, 12Z, etc) |
| Sky Cover Web Service | CONUS displays every hour; OCONUS displays every 3 hours (03Z, 06Z, 09Z, 12Z, etc) |
| Snow Amount Web Service | CONUS/OCONUS (forecast is valid at 00Z, 06Z, 12Z and 18Z) |
| Temperature Web Service | CONUS displays every hour; OCONUS displays every 3 hours (03Z, 06Z, 09Z, 12Z, etc) |
| Wave Height Web Service | CONUS displays every hour; OCONUS displays every 3 hours (03Z, 06Z, 09Z, 12Z, etc) |
| Wind Direction Web Service | CONUS displays every hour; OCONUS displays every 3 hours (03Z, 06Z, 09Z, 12Z, etc) |
| Wind Gust Web Service | CONUS displays every hour; OCONUS displays every 3 hours (03Z, 06Z, 09Z, 12Z, etc) |
| Wind Speed Web Service | CONUS displays every hour; OCONUS displays every 3 hours (03Z, 06Z, 09Z, 12Z, etc) |
| Wind Speed and Direction Web Service | CONUS displays every hour; OCONUS displays every 3 hours (03Z, 06Z, 09Z, 12Z, etc) |
