Heavy rain battering the South has closed roads and caused localised flooding in Mosgiel and Oamaru today.
In Eastern Otago, the MetService predicted up to 40mm of rain would fall in 12 hours from 6am to 6pm today, while in Southland, up to 50mm may fall in the 12 hours from 3am to 3pm.
A heavy rain watch remained in place for Eastern Otago this afternoon, but had been lifted for Southland.
Rainfall was expected to ease in Eastern Otago this evening.
As a result of the rain, East Taieri School has closed for the day because of the risk caused by a rapidly rising creek.
A Dunedin City Council spokeswoman said there was localised flooding in Mosgiel and a couple of road closures were in place around the Silver Stream.
"The Dunedin City Council will continue to monitor the situation and respond as necessary," she said.
Anyone noticing issues with mud tanks or other council infrastructure should call (03) 477-4000 so it could respond.
Fulton Hogan Central Otago District Council engineer Conor Muir warned river levels in the Maniototo were getting high. They were "not a problem at this stage", but the situation was being monitored.
Firefighters from the Oamaru Volunteer Fire Brigade were called to assist an Oamaru businesswoman with flooding issues this afternoon.
A carpark behind the woman's business was flooding about 1.15pm, a Fire and Emergency New Zealand spokesman said, and the woman was "distraught" about the situation.
Firefighters found the flooding was due to a blocked drain. They cleared as much water as they could and advised her to contact the Waitaki District Council to clear the drain and to use sandbags until the water cleared.
Wet week forecast
North Canterbury and the Kaikoura Ranges would also be deluged by heavy rain on Monday.
Many South Island alpine road passes have warnings, with snow expected to fall throughout the day. Despite snow falling yesterday, roads remained open.
The country was expected to stay wet for most of the week, with MetService predicting low pressure systems to dominate.
Thunderstorms were expected to continue to hammer the North Island today.
More than 200 Taranaki homes are without power after a spectacular stormy night knocked out electricity to hundreds across the region.
MetService warned unstable conditions in the skies meant much of the North Island from Northland to Manawatu and southern Hawke's Bay remained at risk of thunder and lightning from midday.
Forecasters warned the thunderstorms were likely to lash many regions with outbursts of heavy rain, hail and strong wind gusts of up to 100kmh.
A far lower risk of stormy weather was likely for the remaining eastern and southern parts of the North Island and top of the South Island.
Last night a lightning bolt struck a piece of public art in New Plymouth, knocking out a light at the tip of the Wind Wand.
Powerco said power was out to 226 homes in Stratford and not likely to be restored until lunchtime today.