If you are waiting for today to get warmer, forget about it.
Dunedin has already set its temperature high for the day - at 6am - when the mercury reached 18.1degC.
The temperature hovered around 18degC for most of the night, until 7am when a southerly change brought rain and sent the temperature plummeting to about 10degC, where it has stayed for the rest of the day.
MetService meteorologist John Law said the unusual phenomenon was caused by ‘‘the Foehn effect’’ - when a moist northwesterly wind dumps much of its moisture on the west side of the Southern Alps before drying and warming up as it heads towards the east coast.
He predicted there would be more warm nights like this to come over the next few months.
Yesterday, temperatures reached 21 degC for most of Otago and Southland, and were as high as 25 degC in parts of Central Otago.
But at 7am, the southerly change also affected inland parts of Otago and Southland, where it brought a light dusting of snow to the higher areas, Mr Law said.
‘‘It’s amazing to think it doesn’t require much to change the weather significantly, particularly this time of year when we can see a real change in the temperatures throughout the day.’’
The weather was expected to be calm and sunny around Otago and Southland again tomorrow, with some light frosts inland.
But Mr Law advised people to make the most of it - the rest of the week would be filled with showers and rain.
A heavy rainfall warning was in place for Fiordland, north of Doubtful Sound, until 1pm today, and for the ranges of Westland, south of Harihari, until 9pm.
Snow for alpine passes
Forecasters have issued snow warnings for South Island mountain passes and the Crown Range Road, linking Queenstown and Wanaka.
About 1cm of snow was expected to fall on the Crown Range summit for about three hours from 2pm today.
MetService said snow could fall to between 700m and 800m on Lewis Pass (State Highway 7), Arthur’s Pass (SH73) and Porters Pass (SH73) in Canterbury from 10pm on Monday until 8am on Tuesday.
LEWIS PASS
From 1am until 8am on Tuesday: Snow is expected to affect the road for a time in the morning. Expect 1 to 3cm to accumulate near the summit, with lesser amounts to 800 metres.
ARTHUR'S PASS
From 10pm on Monday until 3am on Tuesday: Snow is expected to affect the road for a time tonight. Expect 1 to 2 cm to accumulate near the summit, with lesser amounts down to 700 metres.
PORTERS PASS
From 10pm on Monday until 3am on Tuesday: Snow is forecast to affect the road for a time tonight. Expect 1 to 2cm to accumulate near the summit, with lesser amounts down to 700 metres.
- additional reporting ODT Online
