Noble gas data in conjunction with stable isotopes and ¹⁴C ages of groundwater samples from southeastern Wisconsin, USA, indicate a soil cooling of at least 6.5–7 °C during the last glacial period compared with modern soil temperatures. Because stable isotope and excess Ne data indicate that none of the samples contains any signifi cant portions of glacial meltwater, samples with ¹⁴C ages between 12 and 26 ka B.P., which is the time when the study area was ice covered, most likely infi ltrated during short periods of ice retreat or represent recharge containing a signifi cant proportion of precipitation rather than subglacial meltwater recharge. Further, all samples except for those recharged before the last glacial period show a strong correlation between noble gas temperature and δ¹⁸O. By contrast, δ¹⁸O values of samples older than ca. 28 ka B.P. are too heavy with respect to their noble gas temperatures. This might be due to a stronger infl uence of an isotopically enriched moisture source from the Gulf of Mexico . The amount of excess air, which is closely linked to the magnitude of groundwater table fl uctuations, increases shortly before and at the beginning of the last glacial period, suggesting that recharge dynamics changed considerably during that time period.