At high concentration, tropospheric O₃ deteriorates air quality, inducing adverse effects on human and ecosystem health. Meteorological conditions are key to understand the variability of O₃ concentration, especially during extreme weather events. They modify the photochemistry activity and the vegetation state. An important source of uncertainties and inaccuracy in simulating surface O₃ during droughts and heatwaves is the lack of interactions between the biosphere and the troposphere. Based on the biogenic emission model MEGANv2.1 and the chemistry-transport model CHIMERE v2020r1, the first objective of this study is to assess the sensitivity of biogenic emissions, O₃ dry deposition and surface O₃ to biomass decrease and soil dryness effect (using several configurations) during the extremely dry summer 2012. Secondly, this research aims at quantifying the variation of observed (EEA's air quality database, 2000-2016) and simulated (CHIMERE, 2012-2014) surface O₃ during summer heatwaves and agricultural droughts that have been identified using the Percentile Limit Anomalies (PLA) method. Our sensitivity analysis shows that soil dryness is a key factor during drought events, decreasing considerably the C₅H₈ emissions and O₃ dry deposition velocity. This effect has a larger impact than the biomass decrease. However, the resulting effect on surface O₃ remains limited. Based on a cluster approach using the PLA indicator, we show that observed O₃ concentration is on average significantly higher during heatwaves (+18µg/m³ in daily maximum) and droughts (+9µg/m 3) compared to normal conditions. Despite a difference of several µg/m³ , CHIMERE correctly simulates the variations of O₃ concentration between the clusters of extreme events. The overall increase of surface O₃ during both heatwaves and droughts would be explained by O₃ precursor emission enhancement (in agreement with HCHO satellite observations), O₃ dry deposition decrease and favourable weather conditions. However, we simulated a decrease of C₅H₈ emissions (in agreement with HCHO observations) during droughts not accompanied by a heatwave, resulting in a non-significant difference of surface O₃ compared to normal conditions (from both observations and simulations).