This research presents an analysis of a series of thunderstorms which affected Canterbury, New Zealand on 14th December 2009. The case study was used to test the inference that surface heating and local wind convergence are the primary triggers for convective storms in Canterbury. Observational and WRF-ARW simulation data analysis showed that the thunderstorms occurred in a post-frontal synoptic environment with surface wind interactions between the cold southwesterly synoptic wind to the south, the north-easterly sea breeze to the east and a weak northwesterly airflow spilling over the Southern Alps to the north. This surface wind convergence contributed to convective activity and was directly responsible for several of the weaker thunderstorm cells over the central and northern Canterbury Plains. However, the first thunderstorms occurred in the south of the region, over the foothills of the Southern Alps and at some distance from the surface wind interactions further north. Here, orographic uplift was found to be a dominant trigger for convective activity. In addition, frontal uplift around a hitherto undetected weak trough feature was the primary trigger for the main thunderstorm line which spawned a weak (F0) tornado, produced crop-damaging hail and flood-inducing heavy rain over central Canterbury Plains, though local wind interactions likely enhanced the convective activity. Hence, the inference that thunderstorm activity in Canterbury primarily occurs as a result of surface heating and local wind convergence only explained part of the dynamics involved in the convective activity observed.