A study was conducted to evaluate the effect of variations in meteorological parameters on wheat (Triticum aestivum L. emend. Flori & Paol) yields during 1970-2005 and also as simulated with CERES- wheat model. Thetechnologytrendmodel ofhistoricalwheat yields inPunjabindicatedthat over the past2to3 decades, atBallowal Saunkhri, Amritsar, Ludhiana, Patiala and Bathinda the wheat yields have increased@ 64.2, 76.3, 62.8, 87.3 and 71.1 kg/ha/year respectively. Ananalysis of historicalmeteorologicaldataandpastwheat yields revealedthat forJanuary,FebruaryandMarchthemost favourablemaximumtemperatures for wheat yields were in the range of 16.1-18.0 oC, <21.0 oC and 28.1-30.0 oC respectively while minimum temperatures were in the range of 3.1-5.0 oC, 5.1-7.0oC and 11.1-13.0 oC respectively. The simulation study using CERES-wheat model revealed that the temperature increase mostly affected the early (October) sown crop during fourth week of January up to first fortnight of March; the timely (November) sown crop during February and March; the late (fourth week of November) sown crop during March; and very late (December) sown crop during March and first week of April. An analysis of historical wheat yields and weekly meteorological parameters at Ludhiana revealed that during the highyield(>5000kg/ha)cropyears,themaximumand minimum temperatures remained near normal (+ 2oC); the rainfall was also normal or slightly above/below normal under assured irrigated conditions. Frommid-February toMarch, dry and clear weather proves beneficial for grain filling in wheat.On the other hand, during lowyield (<4 600 kg/ha) crop years, although the temperatures were favourable but very heavy rainfall showers were received during the anthesis and grain-filling period ofwheat crop. Theweather also remained cloudy and sunshine hours were invariably below or near normal while the relative humidity remained above (3-10%) or near normal duringmost part of the crop season. Hence, these conditionswereascertainedtobethemostpertinentreasonforrelativelylow-wheatyields.