Torrential rain continues to engulf most of Canterbury this morning, causing widespread surface flooding, road and bridge closures, and some homeowners have had to be evacuated.
Forecasters say the rain is due to ease this afternoon, but they warn another front will sweep in tomorrow and bring a further deluge.
Drivers in the eastern suburbs of Christchurch have been urged to take extra "extreme" care on the quake-damaged roads, which are pot-holed and littered with hollows.
Dudley Creek has burst its bank in St Albans, as has the Heathcote River.
Around 50 council staff and contractors are currently working across the city, monitoring the worst-affected areas and taking steps to address surface flooding, including closing roads, sand-bagging and clearing blockages in the stormwater system.
Banks Peninsula has been the worst hit, with the tourist town of Akaroa receiving a massive 185mm of rain in the last 24 hours.
Lyttelton, where sandbags are being spread to safeguard some houses and shops, has seen 75mm of rain and some residents self-evacuating.
Christchurch International Airport has seen 40mm of rain but is still open. The Ashley River bridge in Waimakariri district has been closed due to flooding.
MetService spokesman Dan Corbett said around 40mm to 60mm of rain has fallen around Christchurch in the last day.
A rain warning will remain in place for much of Canterbury and Otago until tomorrow, he said, as "we're not out of the woods yet".
"The low is sitting and spinning like a car stuck in the mud," Mr Corbett said.
"Because the ground is so sodden in some places, any amount of rain is certainly not needed."
The rain will ease this afternoon, he said, until a second front will arrive from the Gisborne area mid to late tomorrow.
The city council is also bracing itself for high tide, which is due around 2pm today and is expected to increase surface flooding levels, although no houses are expected to be put at risk.
Council's Transport and Greenspace Unit Manager Alan Beuzenberg asked motorists to follow road closure signage and drive slowly on flooded roads.
"As well as the issues of bow-waves caused by vehicles, we are also concerned about the condition of the road under the water. Drivers won't be able to see any potholes and hollows in the road caused by the earthquakes that may have become larger as a result of flooding."
A Fire Service spokesman said there were 39 weather-related calls from the region between about 10pm and 2am, mostly for surface flooding.
Another 15 have been recorded since 6.30am.
The incidents were mostly around Lyttelton and Sumner, already sodden after several periods of heavy rain in the past month.
A property in Rangiora also had to be evacuated due to flooding.
Firefighters had helped about six people from the Mairaki Rd house and organised motel accommodation for them.
