Roughly 500 years ago, maybe more. Recordings are spotty up to the 19th century. Monestaries often had a daily log of current weather, for example. There are likely recovered observations going back to Greek or Roman civilizations.
Average temperatures can be deduced from scientific observations of ice cores and geological records as well. The arctic and antartic ice cores revealed detailed oxygen, carbon dioxide, and particulate data going back a couple million years.
Roughly 500 years ago, maybe more. Recordings are spotty up to the 19th century. Monestaries often had a daily log of current weather, for example. There are likely recovered observations going back to Greek or Roman civilizations.
Average temperatures can be deduced from scientific observations of ice cores and geological records as well. The arctic and antartic ice cores revealed detailed oxygen, carbon dioxide, and particulate data going back a couple million years.