A cool start to spring is about to be replaced by a sudden burst of warmth, according to NIWA meteorologist Ben Noll.
“Parts of Canterbury and Marlborough have been more than 2°C below average so far this month but that’s about to change. It will be more like November than September in a couple of days.
“For the rest of the week and over the weekend, a large area of high pressure is forecast to siphon sub-tropical air across the Tasman Sea onto New Zealand.”
Mr Noll said temperatures are expected to be 5-10°C above average through the end of the working week in the South Island as a foehn northwesterly air flow develops.
Maximum temperatures may reach the low 20s in some inland areas across Otago and Canterbury.
“The unusual warmth is expected to peak on Saturday, with some towns seeing maximum temperatures potentially close to or exceeding 25 degrees.”
Current September maximum temperature records include:
- Waiau (Canterbury), 26.1°C, 2009
- Hanmer Forest (Canterbury), 26.4°C, 1973
- Orari Estate (Canterbury), 27.5°C, 2009
- Balclutha (Otago), 25.5°C, 2006
- Lauder (Otago), 25.4°C, 1966
- Middlemarch (Otago), 24.7°C, 2012
Another very warm day is expected on Sunday before a southerly change ends the run on Monday. But good news - later next week, it is expected to warm back up again.
The North Island will also experience above average warmth, combined with mostly dry weather but it’s not expected to be record-breaking.