Office of Water Prediction Data Services

National Water Prediction Service (NWPS) APIs

This page lists the currently available NWPS data services and links to these services.

NWPS Application API

The NWPS API makes available the data used by the NWPS application, which includes official NWS streamflow forecasts, stream observations, National Water Model streamflow output, crest history, flood impacts, low water history, flood category levels, and location metadata. This service does not contain historical data other than crest and low water history.

NWPS Hydrologic Ensemble Forecast Service (HEFS) API (Experimental)

The experimental NWPS HEFS Forecast API can be used to retrieve real-time and historical HEFS forecast data for NWPS locations. The HEFS is a service developed by the National Weather Service (NWS) to provide ensemble streamflow predictions. HEFS has been implemented at NWS River Forecast Centers (RFCs) for over 3,000 locations throughout the United States. HEFS integrates meteorological forecasts with hydrologic modeling to produce probabilistic streamflow forecasts and other hydrological variables. The service assesses the potential impacts of high-flow events and assesses flood risk. The service currently serves 30 days of data. Guidance from individual RFCs may not be available at all times.