Eastern New Zealand is in for a scorcher this week with predictions temperatures could hit 30degC for this first time this season.
A hot flow of air coming across the Tasman from Australia will result in warmer than average temperatures for much of the country.
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"Look at that surge of warmth!" NIWA says.
"Trans-Tasman air will result in much warmer than average temps for the eastern South Island on Wed + eastern North Island on Thu. Perhaps the first 30degC reading of the season!"
MetService predicts Christchurch will hit 25degC on Wednesday and Timaru and Blenheim will reach 24degC.
Temperatures in the South Island are then expected to fall by the end of the week as a front moves up the country on Thursday, bringing with it a band of "very heavy rain". NIWA warns there's potential for flooding on the West Coast.
The heavy rain is then expected across the top of the South Island from Friday into Saturday.