We use National Centers for Environmental Prediction (NCEP)/National Center for Atmospheric Research (NCAR) reanalysis data to show that Antarctic tropospheric air temperature anomalies result from differences in the daily-mean duskward component, By, of the interplanetary magnetic field (IMF). We find the anomalies have strong geographical and seasonal variations: The mean tropospheric temperature anomaly poleward of 70°S peaks at 0.7 K and is statistically significant at the 1-5% level between 0.1 and 5.6 km altitude above sea level and for time lags with respect to the IMF of up to 7 days. The signature propagates vertically between 1.5 km and 5.6 km. Regional surface temperature anomalies are evident poleward of 60°S and are of diminishing representative peak amplitude from autumn (3.2°C) to winter (2.4°C) to spring (1.6°C) to summer (0.9°C). We demonstrate that these regional anomalies of statistically-significant amplitude are due to geostrophic wind anomalies, resulting from the same By changes, moving air across large meridional gradients in zonal mean air temperature between 60 and 80°S. Our results support the view that IMF-induced changes to the ionospheric electric potential affect the troposphere via the action of resulting variations in the downward current of the global atmospheric electric circuit on tropospheric clouds.