Read here. Across the globe, researchers have found a wide range of evidence indicating the extreme warm temperatures and impact of the Medieval Warming. One of the many characteristics of extreme warming is the change in precipitation levels of the northern latitudes, which experience less precipitation. These regions become much more vulnerable to drought conditions that the extreme warming of climate change brings. For more information on droughts and severe weather, go here.
As peer reviewed research has found, the extreme warming of the Medieval Warming Period is unique and unprecedented, as indicated by the drier (drought) conditions that Finland trees experienced. (click on image to enlarge)
Helama et al. developed what they describe as "the first European dendroclimatic precipitation reconstruction," based on data obtained from hundreds of moisture-sensitive Scots pine tree-ring records originating in southern Finland, using regional curve standardization (RCS) procedures. This work revealed, as they describe it, a "distinct and persistent drought, from the early ninth century AD to the early thirteenth century AD," which interval, in their words, "precisely overlaps the period commonly referred to as the Medieval Climate Anomaly, due to its geographically widespread climatic anomalies both in temperature and moisture.
More historical charts here. Other climate history postings here. Modern temperature charts.