- United States Daily Weather Maps Project
- Historical daily weather maps from 1871 thru 2002 and a link to more recent daily weather maps.
- El Niño Page (National Oceanic and Atmospheric Administration)
- National Climatic Data Center (National Oceanic and Atmospheric Administration)
- Endangered Species Program
- Includes information on threatened and endangered animals and plants. See also the local offices of the U.S. Fish & Wildlife Services.
- Water Resources of the United States
- Includes the Water Data for the Nation, which provides access to years of historical and real-time water data collected by the U. S. Geological Survey.