The summer temperatures may be back but many Wellington beaches are off limits today, with nine beaches declared unsafe for swimming.
Unsafe levels of enterococci bacteria - more than 280 bacteria per 100ml of water - have been recorded at at beaches from Owhiro Bay north to Plimmerton.
The Hutt River also had unsafe levels of the bacteria at the testing site near the Melling bridge, though sites at the river north of Silverstream came back clear from water quality monitoring tests taken on Monday.
Greater Wellington senior environmental scientist Summer Greenfield said the large number of unsafe sites was the result of Monday's downpour.
''In heavy rain, there's a much increased chance of a sewer overflow. We were notified, in Wellington city, Porirua and the Hutt, there were a number that occurred over that Monday and Tuesday period ... plus whatever has accumulated on the streets over [the preceding] dry period.''
Ms Greenfield said enterococci indicates the presence of other bacteria that pose a risk to human health, such as campylobacter and salmonella, which are too expensive to monitor.
The elderly and young children are more at risk of being affected by such bugs, which can cause stomach upsets.
The council's general warning is to not swim anywhere for 48 hours after heavy rain, she said.
''After particularly heavy rain like we had - you can see out in the harbour it's really brown still - I would maybe be a bit cautious about swimming today too.''
She said most sites were expected to return to normal when they were retested later today.
Though some sites - Owhiro Bay, Island Bay, Worser Bay, and Mahanga Bay - had recorded quite high levels of enterococci, more than 3000 bacteria per 100ml of water, these were expected to return to safe levels today.
However, if unsafe readings were found again, local councils would investigate.
Unsafe areas today were:
- Owhiro Bay
- Island Bay
- Seatoun Beach
- Worser Bay
- Scorching Bay
- Mahanga Bay
- Shark Bay
- Hataitai Beach
- Plimmerton Beach
- Hutt River, south of Silverstream
- The Dominion Post
Should Wellington have a new convention centre?Related story: $100m Hilton project back to drawing board