Hard frosts do real damage
Christchurch records among the highest ground-frost counts of any New Zealand main centre — station records vary, but well upward of 70 days a year on NIWA's 1991–2020 climate normals. When a cold snap hits properly the callout volume shows it: during a 2015 frost that took temperatures to −16°C in places, Central Otago plumbers reportedly fielded around 100 burst-pipe callouts in a single week. An older example, but the pattern has not changed. Frozen and bursting pipes are a predictable seasonal event here, not a one-off.