To isolate the stratospheric temperature signal caused by the eruption of El Chich¿n, Mexico (March 28-April 4, 1982) requires consideration of temperature changes of dynamic origin, changes related to the warming of the east equatorial Pacific ocean surface in 1982 (an El Ni¿o event), and changes caused by the quasibiennial oscillation (QBO). Dynamically produced changes in low latitudes associated with sudden warming episodes in the high-latitude stratosphere from January to April are accounted for clearing the way for the diagnosis of temperature changes after April. From composites of stratospheric temperature anomalies during past El Ni¿o events, it was determined that temperature variation related to major sea surface temperature (SST) changes would be negligible in summer 1982 but important thereafter. For summer 1982 the remaining diagnostic problem involved estimating the temperature anomaly that should be caused by the QBO and calculating the residual ascribable to the eruption. From a reconstruction of past QBO cycles and detailed inspection of the most recent cycles, as exhibited in station data near the equator and in zonally averaged temperatures at 15¿--45 ¿N (30 mbar), estimates are obtained for QBO phase with latitude in 1982 and for temperature anomalies caused by the QBO. Residual anomalies ascribed to the eruption amount to approximately 1.0¿--3.0 ¿C between the equator and 35 ¿N. This may be contrasted with total observed 30-mbar anomaly up to approximately 6 ¿C at stations such as Singapore (1 ¿N). Further work for other altitudes and latitudes is needed, with proper acounting of nonvolcanic signals.