Thought last night was warm, or this morning? The sub-tropical flow that covers most of New Zealand is pushing temperatures well above normal nationwide and despite it easing across today in the South Island it may not be clearing from northern NZ all that fast.

With a storm in the Southern Ocean for a week – and high pressure to the north for a week – we don’t have any sudden changes to our airflows. Over the days ahead winds shift from sub-tropical northerlies to Tasman Sea westerlies – except for the very top of NZ.

Across northern NZ sub-tropical airflows look set to remain for today, Tuesday, Wednesday, Thursday, Friday, Saturday – possibly even into Sunday morning before a westerly change finally moves through.

This set up means northern NZ would’ve had about two weeks above normal temperatures to end November and now the first week of December above normal too.

Overnight lows tonight will be high. Here are some examples:

• Some northern and eastern areas may not drop below 20C tonight
• Auckland, Napier & Hastings 19C
• Whangarei, Hamilton, Palmerston North, Masterton, Christchurch 18C
• Tauranga, Gisborne, New Plymouth, Wellington, Nelson, Blenheim 17C

Just because the sub-tropical airflows look set to ease this weekend doesn’t mean they are finished with NZ for now either. Long range data supports the sub-tropical flow returning to the upper North Island possibly around mid next week as the slightly cooler westerly quarter flow from the Tasman Sea/Southern Ocean area continues elsewhere.

– WeatherWatch.co.nz