What winter heating really costs by NZ region
Heating is the single biggest swing on a NZ power bill. For most of the year it barely registers; then June arrives, the heaters go on, and the bill doubles. Space heating makes up around 30% of household energy use nationally, and almost all of it lands in three or four winter months.
What it costs you depends on two things that pull in different directions: how cold your region gets, and what you pay per unit of power. People assume a cheap rate means cheap heating. It does not - a cold climate on a cheap rate can cost more than a mild climate on an expensive one, because you simply need far more kWh to stay warm.
Climate does most of the work
Heating need is measured in heating degree days - roughly, how far and how long the outside temperature sits below a comfortable indoor target. The spread across NZ is enormous:
- Auckland and the north: mild winters, few hard frosts, short heating season. Low heating need.
- Wellington, Tauranga, Nelson: moderate - cool and often damp, not bitterly cold.
- Christchurch and Canterbury: genuine cold, hard frosts, long still nights. High heating need.
- Dunedin, Southland, Central Otago: severe. Cromwell and Central Otago record some of the coldest winter temperatures in the country.
A home in Invercargill or Cromwell can need two to three times the heating energy of the same home in Auckland. That difference dwarfs the difference in rates between regions.
Indicative winter heating cost by region
The table below estimates the monthly winter cost of heating a single living area with a heat pump run about five hours an evening, seven days a week. It combines a realistic heating load for each climate with that region's May 2026 rate. Treat these as ballpark figures - your home, insulation and thermostat habits move them a lot.
| Region | Rate (c/kWh) | Winter heat/mo |
|---|---|---|
| Auckland | 41.0 | $45 |
| Wellington | 37.0 | $52 |
| Nelson | 39.0 | $60 |
| Christchurch | 38.5 | $78 |
| Dunedin | 42.0 | $95 |
| Cromwell | 49.0 | $120 |
Notice the pattern. Wellington has the cheapest rate on the list but costs more than Auckland because it is colder for longer. Christchurch's rate is mid-pack, yet its cost is high because Canterbury winters are hard. Cromwell tops the table on both counts - a high rate and a severe climate compounding each other. The rate is only half the story; the cold is the other half.
Heat pump versus plug-in: the maths
The single biggest lever on your winter bill is what you heat with. A plug-in electric heater - oil column, fan or panel - is 100% efficient: every unit of electricity becomes one unit of heat. That sounds good until you compare it to a heat pump, which does not generate heat, it moves it. A modern heat pump delivers three to four units of heat per unit of electricity it draws.
Put numbers on it. To deliver 2.5 kW of heat to a room for five hours:
- Plug-in heater: draws 2.5 kW electrically. 2.5 kW x 5 h = 12.5 kWh a night. At Christchurch's 38.5c that is about $4.80 a night, or roughly $145 a month.
- Heat pump (COP 3.8): draws 2.5 / 3.8 = 0.66 kW to make the same 2.5 kW of heat. 0.66 kW x 5 h = 3.3 kWh a night, about $1.27 a night, or roughly $38 a month.
Same warmth, the heat pump uses about a quarter of the power. Over a winter that gap is $300 or more, which is why a heat pump pays back its install cost within a few years for anyone heating regularly. See the full breakdown on the heat pump cost page and compare it against the oil column heater.
Why a cheap rate in a cold region still bites
Christchurch is the clearest example. Canterbury's c/kWh is among the more affordable in the country, and yet Cantabrians often face large winter bills. The reason is volume: a frosty, still Christchurch night with the heat pump running for hours simply burns a lot of kWh. A low price on a large quantity is still a large number. A cheap rate helps, but it cannot rescue a poorly insulated home in a cold climate from a big winter bill - only using fewer kWh can.
What actually cuts winter heating cost
- Insulation first. Ceiling and underfloor insulation, and stopping draughts, cut the kWh you need before you spend a cent on heating. It is the highest-return move there is.
- Right-size the heat pump. An undersized unit runs flat out and struggles; an oversized one short-cycles. Match it to the room so it runs efficiently in its sweet spot.
- Zone your heating. Heat the rooms you are in, not the whole house. Close doors to unused rooms rather than warming space nobody occupies.
- Curtains and timing. Thermal or lined curtains, drawn at dusk, hold heat in. Pre-warm a room before you need it and let it coast instead of blasting it cold.
- Set a sensible temperature. Every degree on the thermostat adds cost. 18-20C in living areas is the recommended range; pushing to 24C burns power for little real comfort gain.
Work out your own number
Plug your region, heater type and hours into the NZ Power Bill Calculator to see what your winter heating actually costs, and what switching from a plug-in heater to a heat pump would save you. The methodology page shows the seasonal weighting behind the annual figures.
Related guides
- Insulation vs heat pump: which to do first? - the order that saves the most
- NZ power prices: winter 2026 update - current regional rates
- Power costs in Christchurch and Queenstown - region-by-region detail