An orange heavy rain warning is in force for North Otago, Dunedin, Clutha and northern Tasman with up to 100mm of rain expected to fall, causing MetService to warn of streams and rivers potentially rising rapidly.
Inland parts of Otago and the South Canterbury High Country are also under heavy snow warnings, with up to 35cm likely to fall above 400m. Snow warnings are in place for most high level roads in the South Island.
MetService said travel disruption is possible, as is damage to trees and powerlines.
"If you must travel, drive cautiously, and ensure you have snow chains, sleeping bags, warm clothing, and emergency items," it said in a statement.
Wind gusts in Westland and Fiordland may reach 120km/h on Tuesday and Wednesday, and both regions are under an orange strong wind warning.
High sided vehicles and motorbikes were warned to take extra care driving in these conditions and people should secure items on their property that might be at risk of being blown away, MetService said.
Road snowfall warnings are in place for:
- Lewis Pass (SH7)
- Arthur's Pass (SH73)
- Porters Pass (SH73)
- Lindis Pass (SH8)
- Crown Range Road
- Milford Road (SH94)
- Dunedin to Waitati Highway (SH1)
A heavy snow watch is also in place for North Canterbury high country and the foothills north of the Rangitata River and inland areas of Otago and Southland, as well as eastern Fiordland.
Rain watches are also in place for Bay of Plenty, Taranaki, Marlborough, Canterbury, Westland and Southland.
MetService meteorologist Lewis Ferris said a large weather system is bringing a lot of rain to eastern Southland in particular, along with a risk of widespread snow in the southern parts of the South Island.
"With the system moving in it is bringing in that rain first, however we have already seen some snow already turning up at Homer Tunnel, though that is quite elevated," Ferris said.
"It is through into Tuesday that we expect that snow to fall lower as cooler air moves in and that will affect southern parts of the South Island."
MetService severe weather warnings
Periods of heavy rain and snow for parts of the country, and southeasterly gales for western parts of the South Island.
A low over the Tasman Sea is forecast to affect the country from Monday to Wednesday. Persistent and cold easterlies are expected to develop over the southern South Island, bringing heavy rain and heavy snow above 300 metres. Southeasterly gales are expected to develop over western parts of the South Island late Monday and Tuesday.
Watches and Warnings are in force for a large part of the country.
People are advised to keep up to date with the latest forecasts.
Heavy Rain Warning - Orange
Area: Tasman northwest of Motueka
Period: 12hrs from 10am - 10pm Mon, 29 Jul
Forecast: Expect 70 to 100 mm of rain. Peak rates of 10 to 15 mm/h. Minimal chance of upgrading to a Red Warning.
Impact: Streams and rivers may rise rapidly. Surface flooding, slips, and difficult driving conditions possible.
Action: Clear your drains and gutters to prepare for heavy rain. Avoid low-lying areas and drive cautiously.
Area: North Otago, Dunedin and Clutha southeast of Raes Junction
Period: 30hrs from 9am Mon, 29 Jul - 3pm Tue, 30 Jul
Forecast: Expect 70 to 90 mm of rain. Peak rates of 5 to 10 mm/h. Note, rain is expected to turn to snow above 200 metres during Tuesday. Light to moderate rain is expected for remainder of Tuesday and Wednesday morning. Minimal chance of upgrading to a Red Warning.
Impact: Streams and rivers may rise rapidly. Surface flooding, slips, and difficult driving conditions possible.
Action: Clear your drains and gutters to prepare for heavy rain. Avoid low-lying areas and drive cautiously.
Heavy Snow Warning - Orange
Area: South Canterbury high country and the foothills south of the Rangitata River
Period: 24hrs from 4am Tue, 30 Jul - 4am Wed, 31 Jul
Forecast: Expect 30 to 40cm of snow to settle above 500 metres, with lesser amounts down to 400 metres. Low chance of upgrading to a Red Warning.
Impact: Travel disruption and damage to trees and powerlines possible. Cold conditions may cause stress for livestock.
Action: Prepare for snow, cold temperatures, and possible power outages. If you must travel, drive cautiously, and ensure you have snow chains, sleeping bags, warm clothing, and emergency items.
Area: Inland parts of eastern Otago
Period: 24hrs from 10pm Mon, 29 Jul - 10pm Tue, 30 Jul
Forecast: Expect 25 to 35cm of snow to settle above 400 metres, with lesser amounts down to 200 metres. Low chance of upgrading to a Red Warning.
Impact: Travel disruption and damage to trees and powerlines possible. Cold conditions may cause stress for livestock.
Action: Prepare for snow, cold temperatures, and possible power outages. If you must travel, drive cautiously, and ensure you have snow chains, sleeping bags, warm clothing, and emergency items.
Strong Wind Warning - Orange
Area: Westland
Period: 26hrs from 11am Tue, 30 Jul - 1pm Wed, 31 Jul
Forecast: Severe gale easterlies gusting 120km/h in isolated exposed places. Low chance of upgrading to a Red Warning.
Impact: Damage to trees, powerlines, and unsecured structures possible. Driving may be difficult, especially for high-sided vehicles and motorcycles.
Action: Prepare your property by securing items that can be picked up by strong winds. Drive cautiously.
Area: Fiordland mainly about the Fiords
Period: 36hrs from 8pm Mon, 29 Jul - 8am Wed, 31 Jul
Forecast: Severe gale easterlies gusting 120km/h in isolated exposed places. Minimal chance of upgrading to a Red Warning.
Impact: Damage to trees, powerlines, and unsecured structures possible. Driving may be difficult, especially for high-sided vehicles and motorcycles.
Action: Prepare your property by securing items that can be picked up by strong winds. Drive cautiously.
Heavy Rain Watch
Area: Mount Taranaki/Taranaki Mounga
Period: 9hrs from 3pm - midnight Mon, 29 Jul
Forecast: Periods of heavy rain, and amounts may approach warning criteria. Low chance of upgrading to a Warning.
Area: The Bryant and Richmond Ranges, also the Rai Valley
Period: 9hrs from 3pm - midnight Mon, 29 Jul
Forecast: Period of heavy rain, and amounts may approach warning criteria. Low chance of upgrading to a Warning.
Area: The Westland District
Period: 12hrs from 9am - 9pm Mon, 29 Jul
Forecast: Periods of heavy rain with possible thunderstorms, and amounts may approach warning criteria, mainly about the ranges. Low chance of upgrading to a Warning.
Area: Southland and Clutha about and northwest of Raes Junction
Period: 15hrs from 9am - midnight Mon, 29 Jul
Forecast: Periods of heavy rain, and amounts may approach warning criteria. Low chance of upgrading to a Warning.
Area: Bay of Plenty east of Opotiki
Period: 12hrs from 1am - 1pm Tue, 30 Jul
Forecast: Period of heavy rain, and amounts may approach warning criteria. Low chance of upgrading to a Warning.
Heavy Snow Watch
Area: North Canterbury high country and the foothills north of the Rangitata River
Period: 26hrs from 10am Tue, 30 Jul - noon Wed, 31 Jul
Forecast: Rain is expected to gradually turn to snow above 400 metres during Tuesday where heavy snowfall is possible. Amounts may approach warning criteria. Moderate chance of upgrading to a Warning.
Area: Inland areas of Otago and Southland as well as eastern Fiordland
Period: 33hrs from 9am Mon, 29 Jul - 6pm Tue, 30 Jul
Forecast: Periods of heavy snow above 800 metres during Monday morning, where snowfall amounts may approach warning criteria. Note, snow level is expected to lower to 300 metres Monday night. Moderate chance of upgrading to a Warning.
Issued: 9:58am Mon, 29 Jul
Next update: 9pm Mon, 29 Jul
Action advice supplied by the National Emergency Management Agency.
