Web services provide the ability to access data via the web.  A user can pass arguments that specify what data is wanted to a URL and the server where the URL is hosted will send back the data, generally in a form such as XML or JSON.  For climate data users, this provides a simple way to build their own web tools as well as easily access large amounts of data. 

Applied Climate Information System (ACIS)

The Applied Climate Information System (ACIS) was developed and is maintained by the NOAA Regional Climate Centers (RCCs).  It is designed to manage the complex flow of climate data from the collectors to the end users.  It is a system that delivers operational information derived from historical archives and near real-time climate data.  ACIS provides metadata and climate data information for national, regional and local datasets. 

Datasets included (but not limited to) are: the NWS Cooperative Observer Program, Automated Surface/Weather Observing Systems (ASOS/AWOS), and the Community Collaborative Rain, Hail and Snow Network (CoCoRaHS).  ACIS provides access to gridded datasets such as the Parameter-Elevation Relationships on Independent Slopes Model (PRISM) and climate models like those from the North American Regional Climate Change Assessment Program. 

More information and documentation can be found at the ACIS website.

Climate Data Access Portal (Cli-DAP)

The Climate Data Access Portal (Cli-DAP) was developed by the Midwestern Regional Climate Center and the Western Regional Climate Center.  It provides end-users access to national sub-daily climate data networks.  Metadata, raw data, and calculated statistics including maximum, minimum and average for hourly, daily, monthly and annual time steps can be accessed through Cli-DAP.  Currently, the Automated Surface/Weather Observing Systems (ASOS/AWOS) and the Climate Reference Network (CRN) observations are available.  Other datasets will eventually be added, including regional and local networks.

For more information on Cli-DAP and how to access it, see this description.  To build Cli-DAP queries, see this site.