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A significant spring storm is expected to hit the South island early next week, bringing heavy rain, wind, and possibly some snow.
A MetService spokesman said a deepening low, and an active front preceded by strong and moist northwesterlies, is expected to approach New Zealand from the west on Sunday.
Severe north-west gales are likely in exposed parts of the Canterbury High Country on Monday, along with heavy rain about the headwaters of Canterbury lakes and rivers.
On Tuesday and Wednesday, it was possible severe south to southwest gales would affect exposed parts of southern Fiordland, coastal parts of Southland and Otago, and Banks Peninsula, he said.
The low was forecast to cross southern New Zealand on Monday, then move slowly eastwards on Tuesday and Wednesday.
The front associated with the low was expected to move northeastwards over the South Island and the North Island during Tuesday morning.
Following the front, a very strong and cold southwest flow would spread over the country, and would persist until at least Wednesday.
"On Monday, there is high confidence rainfall amounts will reach warning criteria about Fiordland and Westland, especially about the ranges, with spillover into the headwaters of the Otago and Canterbury lakes and rivers also likely.
"For Southland and eastern parts of Otago, there is moderate confidence of heavy southerly rain on Monday and/or Tuesday.
"Snow will likely lower to around 500 metres in these regions on Tuesday, with heavy snow possible at higher elevations, likely affecting some roads and high country farms,’’ he said.