Does data processing destroy the original data?

Concord Aug 1893
An example of the original weather and climate records archived at NCDC. Station records like this one are available here.

No, the original records are preserved and are available at no cost online. You can access the National Climatic Data Center's (NCDC) U.S. and global records here.

For more technical answers on this topic, visit NASA Goddard Institute for Space Studies' FAQs and NCDC's FAQs.