New Zealand: Severe weather forecast across northern parts of North Island through at least Dec. 28

Severe weather is forecast across most of North Island and far northern South Island through at least Dec. 28. Strong wind gusts, lightning, and hail may accompany storms. Heavy downpours may trigger flooding in low-lying areas and landslides on unstable slopes. As of early Dec. 26, the New Zealand National Meteorological Service (MetService) has issued the following weather warnings across the affected area:

• Red Severe Thunderstorm Warning (the highest level on a three-tier scale): Christchurch City, Selwyn, and Waimakariri.

• Orange Heavy Rain Warning: Gisborne/Tairawhiti, Hastings District north of Napier, and Wairoa District.

• Orange Heavy Swell Warning: Wairarapa from Turakirae Head to Mataikona.

• Yellow Strong Wind Watch: Coastal areas of Hawke's Bay, Gisborne/Tairawhiti, Kapiti Coast, coastal Marlborough, including the Sounds, Taranaki, Wellington, and western parts of Whanganui.

• Yellow Severe Thunderstorm Watch: Bay of Plenty, Coromandel Peninsula, Rotorua, Waikato, and Waitomo.

Authorities will likely issue new alerts or update/rescind existing advisories as weather conditions change over the coming days.

Sustained heavy rainfall could trigger flooding in low-lying communities near rivers, streams, and creeks. Urban flooding is also possible in developed areas with easily overwhelmed stormwater drainage systems. Sites downstream from large reservoirs or rivers may be subject to flash flooding after relatively short periods of intense rainfall. Landslides are possible in hilly or mountainous areas, especially where heavy rain has saturated the soil.

Authorities could issue mandatory evacuation orders for flood-prone communities over the coming days. Where significant flooding, landslides, or strong winds impact utility networks, disruptions to electricity and telecommunications services are probable.

Floodwaters and debris flows will likely render some bridges, rail networks, or roadways impassable, impacting overland travel in and around affected areas. Ponding on road surfaces will cause hazardous driving conditions on regional highways. Authorities will probably temporarily close some low-lying routes that become inundated by floodwaters. The disruptive weather will likely cause delays and cancellations at airports in the affected regions. Flooding will probably block regional rail lines; freight cancellations are likely in areas with heavy rainfall and potential track blockages.

Localized business disruptions are probable in areas impacted by severe weather; some businesses might not operate at full capacity because of damage to facilities, possible evacuations, and some employees' inability to reach work sites