Climate-Data.org is based on two data sources:
Climate-Model by Climate-Data.org
All of our climate data comes from a climate model. The model has more than 220 million data points and a resolution of 30 arc seconds. The model uses weather data from thousands of weather stations from all over the world. This weather data was collected between 1982 and 2012. This data will also be refreshed from time to time.
Location Data by OpenStreetMap.org
All of the location data for the cities is based on data from the OpenStreetMap project. OpenStreetMap is open data, licensed under the Open Data Commons Open Database License (ODbL). The map tiles are licensed under the Creative Commons Attribution-ShareAlike 2.0 license (CC BY-SA).
The OpenStreetMap data has not been modified. This data is refreshed regularly to quickly reflect any changes in the data of the OpenStreetMap project.