The monthly values of standardised climatic water balance (KBWs) and standardised precipitation index (SPI) during the vegetation periods (April to September) of the years 1970-1995 in Polesie Lubelskie were calculated, compared and used to assess the intensity and length of meteorological droughts. The results showed that the values of both indices are closely related: there is a statistically significant functional relationship between KBWs and SPI. The quantification of this relationship, provided in the study, may be useful in estimating the monthly values of KBWs on the basis of those of SPI, as the former values determined in such a way are only slightly lower than the latter. The results of the study indicate that the complex system of meteorological conditions, expressed as standardised climatic water balance, and the variation in precipitation, expressed as standardised precipitation index, have a similar effect on the intensity and length of meteorological drought in the vegetation period. Hence, the KBWs and SPI indices are really useful for research into the relationships between meteorological drought and agricultural drought in such periods.

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