Temperatures in New Zealand's deep south could reach near-record levels.
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MetService is predicting Invercargill could reach 31degC on Sunday - its hottest ever day was 32.2degCin 1921.
Alexandra is also expected to hit 31, Gore 30 and Queenstown 27.
Meanwhile, the overnight temperatures in the upper North Island will reach about 20degC in most places, with warm nights predicted to continue until at least Wednesday.
MetService said a deep low pressure system will move east over the Tasman Sea on Monday, bringing wet weather to the country early in the week.
Many areas of the country will have rain on Tuesday and Wednesday, along with high winds in exposed places.