MetService has issued what is only its second-ever red warning as Canterbury braces for what could be the worst rainfall in a decade.
Red warnings are reserved for only the most extreme weather events, and with forecasts up to 300mm of rain could fall in the higher parts of Canterbury throughout the weekend the public is urged to be prepared.
But the rest of New Zealand isn't safe either, with a number of other severe weather warnings and watches issued around the country this weekend. MetService says almost all regions seeing at least a brief dose of rain - and for the North Island could arrive with thunder and hail as well.
Canterbury flood danger
The place most at risk is Canterbury south of Amberley, where a red warning has been issued for heavy rain. A red warning means take immediate action and act now.
"Between 3:00pm today (Saturday) and 11:00am on Monday, expect 200-300 mm of rain about the Canterbury High Country and foothills, with 80-120 mm about the Plains and the coast. Peak rain rates of 10-20mm/h are expected," MetService warns.
An orange warning has also been issued for heavy rain for the rest of Canterbury, and Marlborough about and south of Kaikoura.
"Between 3:00pm today (Saturday) and 3:00pm on Monday, expect 150-200 mm of rain, with peak rain rates of 10-20mm/h expected Saturday evening and during Sunday," MetService adds.
This rain is expected to cause dangerous river conditions and significant flooding. NIWA's New Zealand Water Model is forecasting a "rapid increase" in river flows across Canterbury on Sunday.
"This is indicated about all of inland Canterbury and extending to the coast in some places, such as south Canterbury in particular," NIWA says.
Its animation shows the rivers most at risk of "extremely high flows".
"Keep yourself up-to-date this weekend and follow the advice of emergency officials," NIWA adds.
Rest of New Zealand
MetService communications meteorologist Lisa Murray says apart from the red warning for Canterbury there is other significant weather around the country which people should be aware of - including "thunderstorms, wind, snow and swell".
There is a heavy rain orange warning for Nelson and a thunderstorm watch also covers parts of Nelson and areas in the top half of the North Island.
There is a strong wind watch for Westland and Fiordland for southeasterly winds approaching gales in exposed places.
There are also concerns for some coastal areas due to king tides and large swell over the weekend, these areas include Auckland, Bay of Plenty and Canterbury.