Carbon and nitrogen cycling are tightly linked to hydrologic conditions in peatlands. Water table fluctuations are known to cause complex and often non-linear relationships with carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) fluxes. Few studies, however, have investigated how forced displacement of gases from peat pores during rain events will contribute to these observed patterns. Thus, we conducted a six-month swamp column experiment to evaluate how 20 mm simulated rain events affected surface fluxes of CO2, CH4 and N2O from peat cores. Six peat cores (45 cm deep, 15 cm diameter) were collected from each of two swamps: a temperate swamp in Southern Ontario and a boreal swamp in the Hudson Bay Lowlands’ headwaters. We took measurements of surface gas fluxes prior to, during, and after simulated 20 mm rain events using the closed chamber method and a trace gas analyzer. We also tracked pore gas and pore water CO2 and CH4 concentrations at multiple depths to understand gas transport through the soil column. We observed elevated CO2 fluxes during rain events that were at least three times higher than pre-water addition emissions. For CH4 and N2O, the magnitude of the observed fluxes depended on the length of time of water table drawdown before water addition. This work will help improve our process-based understanding of the carbon and nitrogen budget during periods of water table fluctuations.