NZ Lightning
New Zealand isn’t a lightning country most of the time. Then once or twice a year a tropical low collides with a cold front somewhere over the upper North Island, or a hot afternoon sets off Canterbury’s foothills, and tens of thousands of cloud-to-ground strikes hit the country in a single night. This page replays those nights โ pick an event below and watch the storm light the country up.
What you’ve just watched
Each white flash is a cloud-to-ground lightning strike, fading from white through cyan to gone over the next second and a half. The map covers the full duration of the event in roughly ninety seconds, so a storm that ran for twelve real hours plays out in a minute and a half. The strike positions are stylised distributions around the storm cells’ actual paths โ we know from public NIWA and MetService reports where the cells were and roughly how active they were at each hour, but the per-strike Vaisala data is paywalled. The result is a faithful picture of the storm’s geography and intensity, not a per-strike replay.
Watch for the way storm cells migrate. The Coromandel 2018 event began as scattered convection over the peninsula and consolidated into intense cells that drifted south-east through Mt Maunganui and out to sea. Canterbury 2017 rolled west-to-east across the plains in classic afternoon-thunderstorm fashion. Northland 2022 stayed put longer, parked over the Bay of Islands as moist tropical air kept feeding it from the north.
Why New Zealand is mostly a lightning-quiet country
Compared to continental landmasses with tropical climates, New Zealand has very little lightning. Most of the country averages fewer than one cloud-to-ground strike per square kilometre per year โ many parts of central Africa, Indonesia and the southern United States record fifty to a hundred times more than that. The reason is geometry: New Zealand is two narrow islands surrounded by cool ocean, and ocean surface temperatures here rarely get hot enough to drive the deep, unstable atmosphere that thunderstorms need. Fronts come through, the wind howls, but the air mass usually isn’t humid or warm enough to brew the towering cumulonimbus cells that produce frequent lightning.
The exceptions are summer convective weather โ when a hot land surface destabilises the air column over the upper North Island or the Canterbury Plains โ and the rare collisions of a tropical low with a cold front. When those collisions happen, especially when warm humid air from the Coral Sea or western Pacific runs into a cold southerly, the result can be hours of intense lightning concentrated over a small area. The 2018 Coromandel event was one of the most extreme such collisions in recent memory.
Where lightning happens in Aotearoa
Lightning strike density isn’t evenly distributed across the country. The hotspots, in roughly descending order of average annual strikes per square kilometre, are:
The Coromandel Peninsula and the Bay of Plenty, especially around Mt Maunganui, Tauranga and Whakatฤne. Warm seas to the north feed moisture in, and the Coromandel range provides the lift that triggers convection. Annual strike densities here can exceed 0.5 per square kilometre.
The Hauraki Plains and Waikato lowlands, where afternoon convection over the warm pasture builds into evening thunderstorms in summer. Cells often cross from west to east, sometimes triggering further activity over the Coromandel as they reach the coast.
The Canterbury Plains, where afternoon heating creates classical “anvil” cumulonimbus that march east-northeast from the foothills toward the coast. Christchurch sees substantial lightning a few days each summer; Mid-Canterbury and the foothills towns see more.
The Far North and the Bay of Islands, particularly during humid late-summer events when tropical air destabilises overhead.
The West Coast sees less than you’d expect โ the air mass that crosses it has usually shed its moisture climbing the Southern Alps, and stable air doesn’t make storms.
How lightning is detected
Two systems detect lightning over New Zealand. The official one is the NZ Lightning Detection Network, operated by Vaisala on behalf of MetService โ a series of antennas around the country that triangulate the radio bursts each strike emits. Vaisala’s data underlies the strike maps that MetService and WeatherWatch publish during major events; it is not freely available outside their commercial subscribers. The second is the Blitzortung network, a global volunteer-run system of low-cost antennas operated by enthusiasts. Their data is shared back through lightningmaps.org and similar community sites for non-commercial use.
Both systems detect cloud-to-ground strikes very accurately โ usually to within a few hundred metres of the actual strike point. They distinguish between positive and negative strikes (positive ones are rarer and tend to carry more energy, often causing the worst damage), and they record an estimated peak current in kiloamperes for each. New Zealand’s largest recorded strikes have exceeded 200 kA, comparable to the most powerful events anywhere on Earth.
Lightning safety
The standard advice is the standard advice: 30/30 โ if you see lightning and hear thunder less than thirty seconds apart, take shelter inside; wait at least thirty minutes after the last thunder before resuming outdoor activity. Inside, stay away from windows, plumbing and corded electronics. In open country, avoid being the highest point in a landscape, avoid lone trees, and squat low with feet together if you cannot get to shelter. MetService’s severe weather outlook flags days when thunderstorms are likely; sign up for their alerts during summer.