Introduction: Monitoring Weather and Climate

Networks of instruments monitor weather and climate at all hours of the day and night, all around the globe. The instruments range from simple, familiar systems, such as thermometers and rain gauges, to complex and distant instruments, such as those attached to ocean buoys and satellites.

Why Pay Attention to Weather?

For as long as humans have been around, they've paid attention to weather and climate. The earliest people watched winds from particular directions and certain types of clouds in an attempt to predict upcoming weather. People who spend a lot of time outdoors still recognize insect, bird, and animal behaviors as signs of changing weather. All around the world, much of what we do depends in some way on our local climate. The types of homes we build for comfort and safely, the crops we grow for food and clothing, and the recreational opportunities we enjoy are all matched to our long-term weather patterns. We strive to understand and predict the weather in order to better our lives.

Early Weather Records

Explorers and pioneers often described their daily weather in handwritten journals and logbooks. As scientists invented reliable, affordable weather instruments and communication and data recording methods improved, people participated in group efforts to collect and share records of temperature, wind patterns, and precipitation. In one example from the early 1800s, an Army physician who was interested in the relationship between weather and the health of the troops ordered a systematic effort to collect weather data. Soldiers at army posts across the country observed and recorded their daily weather and sent their records to a central location. This effort eventually resulted in more than twenty years of systematic weather records for a large part of the country. In 1891, the task of monitoring weather was transferred from the military to a civilian corps, creating the agency we know today as the National Weather Service (NWS).

Monitoring Weather at the Surface

Over the past several decades, scientific organizations established networks of weather-observing stations across the country and around the world. The United States has thousands of official weather stations, and many more volunteer observers who record weather data every day. Many stations have compiled continuous weather records over many decades, but other stations only operated for a few years before stopping. Weather stations where data were collected for some period include:

• 11,700 Cooperative Observer (COOP) weather stations
• 122 National Weather Service (NWS) Offices
• 840 automated stations at airports—maintained by the Federal Aviation Association (FAA)
• 900+ Automated Surface Observing System (ASOS)
• 1,100 additional Automated Weather Observing Stations (AWOS)

For a complete list and full descriptions of each type of station and the data they collect, see Land-Based DataSets and Products »

Monitoring Weather from Above

Just as ground-based weather instruments improved over the years, so too did our ability to measure weather at various heights above the surface. Early methods of monitoring weather from above included the use of kites, balloons, and airplanes. Today, we have a large number of satellites with specialized sensors orbiting the planet, monitoring our weather from miles above.

What Variables Do We Monitor?

How do we know climate is changing? Which variables help us understand climate and detect climate change? An international group of meteorologists and climate scientists have agreed upon a list of essential climate variables (ECVs), that we monitor to help us understand changing conditions. ECVs were selected based upon their feasibility, relevance, and cost-effectiveness, as well as their reliability and consistency. The variables are grouped into three categories: atmospheric (air), terrestrial (land), and oceanic (ocean). For all categories, sensors record both in-situ (in place) and remote measurements.

To learn more about the specific variables we monitor and the instruments we use to measure them see: 

• Air
• Land
• Ocean

Where Do All These Weather Data Go?

As our abilities to record weather observations matured, scientists and government administrators recognized the value of gathering and storing these records in a single place. In 1951, they established what is now called the National Centers for Environmental Information (NCEI). Official weather records—ranging from observers’ handwritten logbooks to early computer tapes to real-time measurements from our array of automated weather stations—are stored at this center. Today, many of these records have been or are being digitized through citizen-science efforts. NCEI makes these records available to the public via the Internet.