Extratropical cyclones (ETCs) drive weather variability and dominate extreme wind and precipitation events in storm track regions. This study investigates ETC responses to stratospheric aerosol injection (SAI) compared to a high-emission (RCP8.5) and a reference scenario, using high-resolution CESM simulations with 0.25°/0.1° horizontal resolution in the atmosphere/ocean. Storm track activity is quantified using 2–6-day bandpass-filtered mean sea level pressure (MSLP), and individual cyclones are tracked using CyTRACK. SAI produces regionally asymmetric responses: the North Pacific storm track shifts equatorward, linked to SST changes, while the North Atlantic storm track shifts poleward, linked to an SAI-induced positive North Atlantic Oscillation (NAO) phase. The RCP8.5 scenario shows the fewest cyclones in both hemispheres, whereas cyclone frequency partially recovers toward reference levels under SAI. A risk analysis linking extreme events to ETCs through combined distance and vorticity masking shows that extreme precipitation events (>50 mm/day) increase by 18 % in both hemispheres under RCP8.5 but decrease by 11 % in the Northern Hemisphere and 6 % in the Southern Hemisphere under SAI. Near-surface wind extremes >25 m/s) decrease by 11 % under RCP8.5 and 5 % under SAI in the Northern Hemisphere, but with different spatial patterns. In the Southern Hemisphere, extreme wind events decrease by 4 % under RCP8.5 and 5 % under SAI. These findings demonstrate that SAI does not simply reverse warming-induced changes but produces new circulation patterns, highlighting the need for regional assessments of geoengineering impacts on midlatitude weather extremes.