Residents in Dunedin and Clutha are advised to clear drains and gutters in preparation for heavy rain and surface flooding.
The weather forecast for the 33 hours starting at 3am on Thursday through to noon on Friday in North Otago, Dunedin and Clutha is for periods of heavy rain, in amounts which "may approach or even exceed" warning criteria.
While an official warning has not yet been issued by MetService, the forecaster said the chances of one being released sometime today were "high".
A brief period of heavy rain was expected this afternoon and evening, before easterly rain set in on Thursday morning.
Niwa data showed normal rainfall in Dunedin could reach 60mm in the month of October, but the rainfall totals over the next three days could exceed that.
MetService said streams and rivers might rise rapidly, and surface flooding, slips and difficult driving conditions were possible.
"Clear your drains and gutters to prepare for heavy rain. Avoid low-lying areas and drive cautiously."
Emergency Management Otago stakeholder engagement adviser Erica Andrews said the organisation would continue to keep a close eye on the situation, and advised residents to keep up to date with the latest forecasts and check their website for information.
In Clutha District, up to to 100mm of rain was expected over the next three days.
In a statement, the council said today contractors were working around the towns checking that sump tops are clear. Residents were asked, if they were able, to check the drains outside homes.
"Due to the size of the network, should there be any flooding, signage will be prioritised accordingly with regular updates sent out via Antenno, the council's website and council's Facebook page.
"It is expected that any surface flooding will be widespread so we ask that everyone takes care on the roads and avoids driving through areas of deep flooding where possible. If you come across any flooding that we recommend notifying the council via Antenno or phone (0800 801 350)."
Snow for alpine areas
A heavy snow watch has been issued for Central Otago and the Queenstown Lakes District in the 12 hours from noon today. MetService said periods of snow may occur above 800 metres, where snowfall amounts could approach warning criteria.
Alpine roads set to be affected.
The Lindis Pass (State Highway 8): Rain was expected to turn to snow from 5pm on Wednesday until 3am on Thursday. Up to 3cm could to settle near the summit, with lesser amounts to 800 metres.
The Crown Range Road, linking Queenstown and Wānaka: For 12 hours from 3pm, rain will turn to snow in the afternoon and up to 4cm could settle near the summit, with lesser amounts to 700 metres.
In Southland, the Milford Road (SH94) is closed from East Gate (Hollyford) to Donne River (Westgate) on Wednesday as rain has increased the chance of avalanche, Milford Road Alliance said.
MetService has issued a heavy rain watch for Southland, about and north of SH94. For the next 12 hours from midday, the rain was expected to turn to snow and up to 4cm may settle near the Homer Tunnel, with lesser amounts to 800 metres. Snow showers would turn to rain on Thursday.
"It is possible the road will be closed overnight on Wednesday," Milford Road Alliance advised.
- additional reporting ODT Online
