The aim of this study was to evaluate the trends of climate change on the Kashubian Lake District and to determine the impact of expected trends on groundwater resources. The analysis of trends in temperature and precipitation was conducted for the six-decade history of meteorological measurements at the weather station in Koscierzyna. The analysis shows the trend of temperature increase of +0.0182ºC/year. The highest increase in temperature is observed in the months from January to May, and in July and August. Annual precipitation also shows a growing trend. This is on average 1.847 mm/year, while the largest increase relates to the months from January to March and from October to December. These trends may contribute to an increase in the recharge rate. Precipitation grows mainly in the non-growing season. If the current trends are maintained, the sum of precipitation involved in the groundwater recharge will probably increase by 36 mm (5.5%) over the next 50 years. The groundwater flow model (MODFLOW) calculation made for these projections showed primarily a tendency for increased descending seepage between aquifers and a slight decrease in upward flow. The most significant changes are observed in the shallow layer, were spring outflows increases by 12%, and the water table rises by about one meter.