Water of Leith was rising rapidly in Dunedin. Photo: RNZ / Tess Brunton
When it rains in coastal Otago, which is not often, it would usually pass over from the west or the south-west.
"So, there might be a burst of heavy rain as that front moves across," MetService meteorologist Lewis Ferris says.
But what was happening today was different, leading to the first use of the red rain warning in the area, the highest level of MetService's colour-coded weather warnings that were introduced in 2019.
"In this case, with the weather funnelling in basically directly from the east, that rain is going to linger," Ferris said.
"It's basically already been raining for 24 hours and we are expecting those rain rates to increase this evening and really persist into Friday."
MetService had given North Otago, Dunedin and coastal Clutha a red rain warning for 34 hours. It began at 11am on Thursday and runs until 9pm on Friday.
It said there was "threat to life" from dangerous river conditions, significant flooding and slips.
Red rain warnings were the highest level of warning MetService issued.
Ferris said in an event like a cyclone, several regions would be issued with red warnings, and possibly even wind warnings, too.
"In this case it's one region really getting the worst of the weather," Ferris said.
Flooding signs have been put up on roads to warn motorists. Photo: RNZ / Tess Brunton
Emergency Management Otago has teams on the ground, ready to respond to any impacts the severe weather may bring.
Group manager Matt Alley told Checkpoint there had been steady rain throughout the day and "everything" was saturated.
Evacuations were not expected, although Alley said people in low-lying areas should be ready to leave if they see water coming.
He urged people not to wait to be told to leave - to do it if they thought it necessary.
If evacuations were needed, people might be door knocked by officials or receive an emergency alert to their mobile.
He said people in low-lying, flood-prone areas should not enter floodwaters or drive through them.
People with stock or cattle were encouraged to move them to higher ground if they were in low-lying areas.
People are giving away sandbags in Dunedin. Photo: RNZ / Tess Brunton
Slips that may occur could affect power and/or communication if they took out lines and cables, Alley said.
Meanwhile, a Boil Water Notice will be in place for Omakau/Ophir from 6pm.
Residents and visitors were asked to boil all water they will be using for drinking, food preparation, cooking and cleaning their teeth until told otherwise.
Water tankers will be made available at Omakau Domain and Swindon Street in Ophir.
MetService said the majority of warnings issued by MetService are orange. Red Warnings are reserved for the most severe weather when significant disruption and safety issues are expected.
Since 2019, New Zealand has only had 15 red rain warnings, including during the Canterbury flooding in May 2021, the 2022 flooding in Gisborne and Wairoa, the 2023 Auckland floods, and Cyclone Gabrielle.