Written records from 17th-century Transylvania tell a story of frequent severe winters, shifting rainfall and repeated strains on harvests and communities. A historical climate reconstruction by Ovidiu Razvan Gaceu and coauthors, published in PLOS Climate on October 28, 2026, suggests that the region’s weather was highly variable, with cold extremes and reports of excess precipitation more common than reports of deficit.
The team assembled 937 distinct testimonies from 68 localities. They drew on chronicles, diaries, registers, books and other historical accounts, including descriptions of weather as well as indirect clues such as crop damage, river conditions and disruptions to travel. These are not continuous measurements: the documents were generally written for other purposes and tended to record unusual events. The authors coded the evidence using shared criteria, with two researchers classifying records independently and a third reviewing disagreements. They also required multiple independent accounts to confirm events included in the analysis.
Cold winters stand out in the reconstruction. The records identify 55 winters as particularly harsh, including 36 in the period from 1645 to 1700, during the Maunder Minimum, an interval of exceptionally low solar activity. The authors report that winters after 1645 were predominantly very cold, though warm seasons and other exceptions show that the cooling was not constant. Across the century, the records also include unusually warm summers and winters.
Precipitation varied as well. The study counts 77 mentions of excess precipitation across 51 years, compared with 40 mentions of deficit across 35 years. The excess included heavy winter snowfall, rain and floods; droughts also occurred, including several dry spells in the 1630s. The authors found no prolonged stretch of the century defined only by excess or only by deficit. They caution that conditions could differ across Transylvania: a report of heavy rain in one area did not necessarily describe the whole principality.
The records also connect climatic extremes with poor harvests, higher prices and hunger. The study identifies 20 years with poor harvests and 26 with inflation and famine, while noting that crop losses could also involve pests and other adverse conditions. Epidemics appear in the documentary record too. The authors argue that climate could contribute indirectly, as harvest failures and food scarcity left people more vulnerable and could favor the spread of disease. They explicitly distinguish that role from the direct cause of plague, the bacterium *Yersinia pestis*. Political instability, military campaigns, conflict and economic inequalities also increased vulnerability; climate was a compounding stressor, not the sole cause of crises.
The team compared its historical reconstruction with natural climate records, including cave ice and precipitation proxies. Those comparisons generally support notable climate fluctuations and wetter conditions in parts of the later century, but they do not match perfectly. Differences in local climate, the uneven distribution of records and possible delays in cave ice signals are among the explanations discussed. The authors describe low solar activity as a plausible contributor to cold conditions and note that volcanic eruptions may also have played a role. However, they say the links between eruptions and local cold events are inconsistent, so timing alone does not establish a direct cause.
The reconstruction’s reach is limited by what survived and what people chose to record. Historical coverage is uneven, with more accounts from larger, literate communities; gaps may represent ordinary weather, missing documents or events that went unrecorded. Some records describe brief, local conditions that cannot safely be generalized to a full season or year. The authors say additional accessible accounts may refine the picture.
By combining documentary evidence with climate proxies, the study adds a regional account of how people experienced climate variability before instrumental records. Its central lesson is specific to this reconstruction: cold and wet extremes interacted with existing social pressures, and their effects depended on where and when they occurred. That detail can help historical climatologists examine how communities faced environmental stress, while the study does not claim that one historical episode provides a direct template for present-day climate impacts.