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Historical climatology has remarkable potentialities to produce climatic reconstructions with high temporal resolution. However, some methodological limitations hinder the spatial development of this discipline. This study presents a new approach to historical climatology that overcomes some of the limitations of classical approaches, such as the rogation method or content analysis: the Cost Opportunity for Small Towns (COST). It analyses historic documents and takes advantage of all sorts of meteorological information available in written documents, and not only the severest events, to therefore overcome the most prominent bottlenecks of former approaches. COST relies on the fact that using paper is very costly, so its use to describe meteorological conditions is hypothesised as being proportional to the impact they had on society. To prove the validity of this approach to reconstruct climate conditions, this article exemplarily uses the Municipal Chapter Acts of a small town in southern Spain (Caravaca de la Cruz), which span the 1600-1900 period, and allows reconstructions to be obtained on a monthly basis. Using the same documentary source, the three approaches were used to derive respective climate reconstructions, which were then compared to assess climate signal consistency and to identify possible caveats in the methods. The three approaches led to a generally coherent series of secular variability in the hydrological conditions, which agrees well with previous study results. The COST approach is arguably more objective and less affected by changes in societal behaviour, which allows it to perform comparative studies in regions with different languages and traditions.