Peatlands are among the largest stocks of soil carbon, which can be stored for thousands of years under well-wetted conditions. The main goals of the study were to assess annual and seasonal CO₂ balances of a temperate peatland and the main biophysical factors affecting these CO₂ fluxes. The studied peatland was usually a CO₂ sink with a mean annual net ecosystem production (NEP) of 110±83 gCO₂-C·m⁻²·yr⁻¹ and extreme balances in 2006 (-17 gCO₂-C·m⁻²·yr⁻¹) and 2011 (194 gCO₂-C·m⁻²·yr⁻¹). Annual fluxes were not significantly correlated with biophysical variables, unlike seasonal data. Furthermore, the average air temperature in spring and summer was related to NEP at r²=0.65 and r²=0.61, respectively (warmer spring increased NEP while hot summer decreased NEP in these seasons). A decrease in daytime measured NEP during the summer period (June-August) was observed when TA exceeded 25 °C or VPD was above 15 hPa, respectively, due to the growing R_eco and possibly plant photorespiration. These findings suggest a negative impact of ongoing global warming on temperate peatland CO₂ balances.