Many previous studies have investigated the role soil moisture-rainfall feedbacks may play in maintaining drought conditions in arid/semiarid regions. This study presents observational evidence that vegetation may also be an important factor in modulating the terrestrial/atmosphere interactions in these regions. By analyzing the Granger causal relationships between monthly anomalies of NDVI, precipitation, and temperature over the Northern Hemisphere during the growing season (April-October) for 1982-2000, we identified significant intraseasonal influences of vegetation upon climate over semi-arid regions in the mid-latitudes (e.g., the North American and the interior Asian grasslands). The signs of these causal relationships show that while positive precipitation anomalies usually promote vegetation growth in these regions, enhanced vegetation may induce lower rainfall but increase temperature. The positive influence of rainfall and the negative feedback of vegetation lead to the possibility of oscillations in both fields. Analysis of the power spectra of area-averaged precipitation indices indicates that such oscillations occur with periods of 4-8 months in the North American and the central Asian grasslands. Altogether, the results suggest a physical mechanism in which initial enhancement of vegetation may lead to lower soil moisture via enhanced evapotranspiration; the subsequent drying of soil in turn leads to higher temperatures and lower rainfall. Evidence exists that these feedbacks (and oscillations) intensify under drought conditions, suggesting that vegetation activity may help to stabilize precipitation variability in the arid/semiarid mid-latitudes, particularly during years with low overall rainfall.