U.S. Climate Reference Network

The US Climate Reference Network (USCRN) is a network of climate stations developed and maintained by the National Oceanic and Atmospheric Administration (NOAA). The purpose of the USCRN is to maintain a sustainable high quality network which will detect, with high confidence, signals of climate change in the US. As of 2023 it consists of 137 commissioned stations located in the Contiguous United States, Alaska and Hawaii.

Purpose
The goal of the USCRN is to provide to the general public, free of charge, long-term high-quality observations of surface air temperature, precipitation, and other climate indicators that can be coupled to past long-term observations for the detection and attribution of present and future climate change. It provides the United States with a reference network that meets the requirements of the Global Climate Observing System.

Background
In 1997 the World Climate Research Programme convened a meeting to determine the state of the art of climate research around the world. One of the principle conclusions of that meeting was that the global capacity to measure major climate variables such as temperature, rainfall, wind speed and direction, was inadequate to inform efforts to confront the emerging issue of climate change. This warning was reinforced by America’s National Research Council in their 1999 report that called for a national effort to create decision support systems that could support these efforts.

The US response to this challenge was organized by the NOAA. The result was the USCRN that collects major climate variables, which are then assembled by the National Centers for Environmental Information into a database and made available, free of charge, to the public.

The first prototype of a USCRN station was constructed in North Carolina in the year 2000. The USCRN was commissioned January 2004, and the continental United States network of 114 stations was completed in 2008.

The Network
As of 2023 the USCRN consists of 114 stations in the continental US, 2 stations in Hawaii, and 21 stations in Alaska.

This map shows the 2023 locations of all USCRN stations.

The USCRN is managed and maintained by the Surface-Atmosphere Exchange, a department of the Air Resources Laboratory, a division of NOAA Research. The National Centers for Environmental Information maintains and distributes the USCRN database of observations and derived climate products.

Stations
Each station is positioned in a pristine site which is representative of the climate of the region and expected to remain free from development over coming decades, in order to avoid, for example, possible urban microclimate interference.

Each station may include the following sensors:


 * Air temperature


 * Surface temperature


 * Precipitation


 * Soil moisture


 * Solar radiation


 * Wind speed


 * Relative humidity

The data base
Collecting readings from the USCRN stations, organizing them into a database, and making them available to the public is managed by the National Centers for Environmental Information, a component of the NOAA.

An example of the reports available is this chart that shows the average surface temperature anomaly for the continental US for the period January 2005 to October 2023.

In this context anomaly is defined as a deviation from a trend established from historical observations of temperature. For this chart, the trend is expressed as zero degrees Fahrenheit (0˚F) on the left vertical axis and zero degrees Celsius (0˚C) on the right vertical axis. Each point on the graph represents the extent of the deviation of each temperature reading from this calculated trend.