USGS provides access to over 135 years of high-quality and discoverable water data collected at more than 1 million monitoring locations across the United States and territories.

WaterWatch is a U.S. Geological Survey (USGS) World Wide Web site that displays maps, graphs, and tables describing real-time, recent, and past streamflow conditions for the United States.

The Regional Climate Centers (RCC) Applied Climate Information System (ACIS) offers interactive temperature and precipitation charts with single- or multi-station capabilities.

Precipitation data from CoCoRaHS: a non-profit, community-based network of volunteers of all ages and backgrounds working together to measure and map precipitation (rain, hail, and snow) across the U.S.

The National Weather Service's National Water Prediction Service (NWPS) provides river stage observations and forecasts and long-range river flood outlooks across the lower 48 United States, Puerto Rico, and Alaska. 

The NOAA NCEI Climate at a Glance (CAG) tool provides an analysis of monthly and annual temperatures for the globe and is intended for the study of climate variability and change.

Global Historical Climatology Network (GHCN): an integrated database of daily climate summaries from land surface stations across the globe, including a common suite of quality assurance reviews. 

North American Drought Monitor: A collaboration between the U.S., Canada and Mexico to create a monthly continental drought monitor.

Quick Drought Response Index (QuickDRI): a geospatial tool that characterizes the intensification of short-term drought condition patterns on a weekly basis across the continental United States (CONUS) at a 1-km gridded spatial resolution.

The U.S. Drought Monitor is a map updated each Thursday to show the location and intensity of drought across the country.