Questions asked after monsoon-like rains sweep Wellington

Questions are being raised about the cause of flooding in parts of the capital.

Wellington residents reported torrents surging down Tinakori Road in Thorndon on Saturday morning and rising around parked cars, with some joking a boat or kayak lane was needed on the busy street.

MetService issued a Severe Thunderstorm Warning for Wellington for the morning, including for torrential rain, after thunderstorms were detected near the city and airport, moving east-northeast. The formal alert was extended during the morning, before later being lifted.

Wellingtonian Rebekah Ward described watching floodwaters rising towards the doors of shops in Tinakori Road, while having breakfast there.

She said the "river" of water rose to the bottom of parked cars and even knocked over a scooter, prompting fears her own vehicle could be swept away.

The timing of the downpour was an "ironic" reminder of the monsoon she would soon experience on a trip to India, Ward said.

"There were cars parked along Tinakori Road and the water was getting higher and higher and higher... and I could see that the water was getting up to the level of the bottom of the car door, and I was thinking 'oh gosh, am I going to have a car when this is finished?'

MetService meteorologist Paris Marshall said multiple reports and observations of hail and intense rainfall were logged across the capital on Saturday morning as the storm moved east toward Lower Hutt.

The intensity was at a level where flash flooding around streams, gullies and urban areas were possible, and instruments recorded 40 millimetres of rain in half an hour at MetService's Kelburn station, near Tinakori Road, Marshall said.

Fire and Emergency NZ said it had no weather-related callouts from the downpours.

Responding to commentary on social media, Wellington's deputy mayor Ben McNulty said three-water provider Tiaki Wai should investigate what went wrong, adding that the area had not flooded significantly during heavy rain events earlier in the year.

Tiaki Wai was approached for comment.

However, Tiaki Wai did issue an alert that heavy rain had lead to a discharge of fully treated wastewater into the Waiwhetū Stream, in Lower Hutt, which empties into Wellington Harbour.

This could make the water discharge appear cloudy or murky or mean it has an odour, they warned, and all recreational water users should follow Land Air Water Aotearoa (LAWA) advice and stay out of the stream the next two to three days.

The LAWA website had all swimming spots on the north and east of Wellington Harbour as well as Oriental Bay marked as unsuitable for swimming, on Saturday.

Snowfall warnings issued for high parts of the country, strong wind watch for Auckland

Elsewhere in the country, MetService issued snowfall warnings for the Desert Road (SH1) and Lewis Pass (SH7), while strong southwest winds prompted a yellow Strong Wind Watch for Auckland, through till 7pm Saturday.

Snow was expected to settle on Desert Road from late Saturday afternoon and into the evening, with 2 to 4cm possible near the summit and light flurries down to 800m.

Snow showers were possible on Lewis Pass on Saturday afternoon and evening with 1 to 2cm of snow accumulated.