The data comes from weather stations all across the US, which I assume are managed or operated by NOAA. This project is at the World Meteorological Organization

The data comes from weather stations all across the US, which I assume are managed or operated by NOAA. This project is at the World Meteorological Organization, an international organization of weather organizations - of which the NOAA is a member. Presumably this means it's official NOAA data. With some minor effort you could extract the raw data, in JSON form, from https://www.wmo.int/cpdb/climate/climate_normal/per_country/USA/source:dashboard https://www.wmo.int/cpdb/climate/climate_normal/per_country/... If I remember correctly the data came from a CD-ROM with historical data. When we put it online the data was already 20 to 25 years old. It was nevertheless the most recent data that we had available, I don't remember the reason why we didn't have anything more recent. The PHP source is (or was) a CakePHP application, and honestly isn't that interesting. There was not more data in the PHP application than what is presented here. EDIT: It was already a messy application when I got there, I cleaned it up as well as I could, but after I left it seems to have gone downhill again. Ah well. Not my problem anymore.