ICOADS is the world's largest collection of in situ marine surface observations with about 240 million records spanning 1784 through a current date. This dataset is the monthly summaries of the observations. The monthly time series are available at 2-degree (all data) and 1-degree (since 1960) spatial resolutions. After the observations are summarized the data are not interpolated or analyzed to fill data voids. The spatial coverage varies depending on the date and position relative to major ocean shipping routes. A monthly summary for an area box includes ten statistics (e.g. mean, median, standard deviation, etc.) for 22 observed and computed variables (e.g. sea surface and air temperature, wind, pressure, humidity, cloudiness, etc.).

ICOADS is the result of a long-standing (beginning in 1981) cooperative project among the NOAA Earth System Research Laboratory, NOAA National Climatic Data Center, and NSF National Center for Atmospheric Research. Systematic quality assurance and processing of many international data sources into a uniform data format make the dataset a significant and often cited archive.

The ICOADS observations are also available , as is much more information on the ICOADS project website