Scorchers to start the week but stormy weather's on the way

Monday, 29 January 2018

The scorching weather continues with temperatures expected to get into the mid-30s on Monday and even hotter on Tuesday, but there is a change on the way and it could get stormy.

MetService meteorologist Raveen Das said the forecast high for Monday was 35 degrees Celsius 'but that's plus or minus 1 or 2'. Towns expected to have the top temperature on Monday included Alexandra, Clyde, Cromwell and Twizel.

For Tuesday the maximums were expected to be in a similar sort of range. 'I would say mid to low 30s tomorrow again,' Das said, while Niwa has said there was a chance temperatures could even hit 40C.

But a big change could be on the way: 'After a month of almost relentless hot and dry conditions over much of New Zealand, it seems we are on the verge of some severe weather,' MetService said.

**READ MORE:

* Heatwave heading Wellington region's way

* Why the weather's always better at your place

* 40 degrees Celsius 'a distinct possibility'

* Warm and wet, is this our new summer?

* Highest temp in NZ for seven years recorded**

Niwa Weather forecasting principal scientist Chris Brandolino said Tuesday and Wednesday were likely to be the two hottest days.

'If we're going to hit 40 … It's in the conversation, it's not a slam dunk but there'll be one or two spots that come really close, maybe just barely touch it,' he told The AM Show.

He did not expect the New Zealand record of 42.4C on Rangiora, set on February 7, 1973 would be broken.

To get to around 40C it was necessary to have hot air coming from Australia, and it was also necessary to have the west wind coming over the Southern Alps and warming as it came down the mountain. 

'I think we're missing the second one, that is a gusty wind, which is a good thing because we don't want the fire risk to get out of control,' Brandolino said.

'Basically you have to mix air to heat it. You can do that from the sun, or mechanically from going down a mountain.'

RAIN, GALE FORCE WINDS

'From Wednesday through to the end of the weekend we see the potential for a lot higher rainfall figures that we have seen for a while which will also be accompanied by gale force winds.'

A tropical depression over the Coral Sea west of Vanuatu had a high risk of deepening into a tropical cyclone. If it did it would be the first tropical cyclone of the season for the southwest Pacific. 

'It also looks likely that this system could track southwards towards New Zealand by the end of this week, although it won't be a tropical cyclone it will still be packing a punch,' MetService said.

Das said humidity could increase in the middle of the week, as tropical air was dragged down over New Zealand. 'It's going to feel even worse,' he said.

Then by Thursday, a south to southwest change was forecast to be moving up the country by Thursday. 'That should cool things down.'

HOT WITH CHANCE OF THUNDER

Auckland is expected to have a mostly fine Anniversary day Monday with easterly breezes and a high of 29C. Wellington is forecast to have light winds, a fine day after late cloud clears, and a high of 27C.

Christchurch is expected to stay relatively cool, with a high of 25C, and a fine day with a northeasterly developing. Things are forecast to warm up, with a high of 32C forecast for Tuesday, then 34C on Wednesday, but on Friday the forecast high is just 18C.

MetService warns the combination of very warm, humid conditions and light winds could spark thunderstorms about the central North Island and inland parts of the South Island in the afternoon and evening.

Thunderstorms to the east of Taranaki could become severe, with downpours of 25 - 35 millimetres of rain possible.