NCEI is currently moving its data and applications to the cloud. This upgrade may result in temporary data access delays. Please see main article link and Frequently Asked Questions for more information and resources.
Please note: Due to scheduled maintenance, many NCEI systems may be unavailable August 11, 10:00 AM ET - 5:00 PM ET. We apologize for any inconvenience.
Reanalyzed datasets can be used to create a coherent, long-term record of past weather by compensating for the inherent biases of the different instruments used to take measurements at different points in the history of weather observation. Reanalysis involves a variety of data synthesis methods that are used to incorporate different datasets into one regularly spaced grid. This ‘gridding’ process makes it easier to compare observations from different datasets, and preserves the original data collection model to ensure that the historical record isn’t influenced by artificial factors.