'Subtropical Auckland'?

[Simon Culling]

Metservice tweet gives the max at Hamilton Airport as 6.3*C for the 3rd. They state that this is the second coldest after 1986 (3.4*C). Here in the UK a day of persistent radiation fog in winter can dramatically reduce the max temperature even in a mild winter. What would be the lowest max for Auckland in winter?

[David]

What would be the lowest max for Auckland in winter?

From memory 7.6C. Don't have the data handy though, someone else might be able to confirm...

[Nev]

Metservice tweet gives the max at Hamilton Airport as 6.3*C for the 3rd. They state that this is the second coldest after 1986 (3.4*C). Here in the UK a day of persistent radiation fog in winter can dramatically reduce the max temperature even in a mild winter. What would be the lowest max for Auckland in winter?

Yes, I saw that, although I suspect the 7.0C on MetService's Hamilton page is likely to be more accurate.

I think the lowest T-max David is thinking of is the 7.7C recorded at the now defunct Owairaka central isthmus site in July 1952.

Auckland has, or has had, quite a few sites. The lowest T-max MetService's main Auckland Aero site has recorded is 8.1C in Aug 2011. However, the lowest for NIWA's main Mangere site about 4-5 km away is 8.4C in July 1996. Also in July 1996, Owairaka recorded 8.0C and Auckland City recorded 7.9C. And the lowest T-max for the city's older Albert Park site is 7.8C in July 1930.

[Simon Culling]

Thanks for the statistics Nev. 8*C as a coldest day for a climate considered to be sub-tropical might be seen as quite low, but it would be interesting to know the weather on the days you mentioned and whether fog or perhaps prolonged rain was involved. I see from the Wikipedia page that Auckland Airport also has a July minimum of -3.9*C which must have been quite a shock to the system!

[NZstorm]

Thanks for the statistics Nev. 8*C as a coldest day for a climate considered to be sub-tropical might be seen as quite low, but it would be interesting to know the weather on the days you mentioned and whether fog or perhaps prolonged rain was involved. I see from the Wikipedia page that Auckland Airport also has a July minimum of -3.9*C which must have been quite a shock to the system!

Those low maximums occurred on cold unstable showery days where the sun did not break through.

The -3.9C at Auckland Airport I am not aware of. They can get heavy frost at Whenuapai in the west, which is perhaps where that reading occurred.

[Nev]

The -3.9C was recorded at Akld Aero in July 1965, which is exceptional for a site that rarely gets below zero. But yes, for more sheltered inland sites like Whenuapai Aero and Ardmore Aero, not so rare.

METARs for Aug 15, 2011 do suggest a mostly wet, stormy day with SSW gales. However July 4, 1996 looks more like an 'anticyclonic gloom' day with light SSE'ers.

Not sure I'd entirely agree with NIWA's description of Auckland being 'subtropical' though, perhaps in our 'Winterless North', but I'd say Auckland has more of a 'temperate-maritime' climate...

[spwill]

Not sure I'd entirely agree with NIWA's description of Auckland being 'subtropical' though, perhaps in our 'Winterless North', but I'd say Auckland has more of a 'temperate-maritime' climate...

I think vegetation is a good indicator of climate type. I am happy to call the coastal zones of northern NZ including Auckland sub tropical.

[Richard]

I think vegetation is a good indicator of climate type. I am happy to call the coastal zones of northern NZ including Auckland sub tropical.

And i reckon its where the mangrove starts to appear that indicates nearing that sub tropical zone.

[spwill]

For me other vegetative indicators of sub tropical are you can grow the likes Citrus, Advacado and Macadamias commercially.

[Richard]

For me other vegetative indicators of sub tropical are you can grow the likes Citrus, Advacado and Macadamias commercially.

Not so much Citrus because mandarins grow very well outside around here, Maya Lemons not quite as hardy, Advacado very much so.

[NZstorm]

Northland is 'warm temperate' zone.
The Kermedecs is the only part of NZ in the subtropics.

[Nev]

I think the term 'subtropical' was meant more metaphorically, rather than literally, although I wouldn't expect to see frosts in a subtropical climate. By 'temperate-maritime' I meant that Auckland doesn't really get extremes in temperature, partly because it's closely flanked by surrounding seas.

Similarly, even though we're nowhere near a continent, eastern and central areas of the South Island are often described as having a 'continental climate', due to the Southern Alps having a similar effect on their climate to that of the Alps in Europe.

[cbm]

The -3.9C was recorded at Akld Aero in July 1965, which is exceptional for a site that rarely gets below zero. But yes, for more sheltered inland sites like Whenuapai Aero and Ardmore Aero, not so rare.

Is it known for certain that was recorded at the present day site? According to Te Ara, Whenuapai was operating as Auckland's main commerial airport at that time. Any chance that has created confusion in the records?

[Nev]

^ Yes, Auckland Airport was under construction at the time and the first international flight flew out in Nov 1965. According to NIWA's notes, there was a Met Observing Office there on Wiroa Island, which is attached to the SE end of the runway. They also mention an instrument enclosure about 30 yards south of the Office. Unfortunately NIWA only appear to have monthly data from June 1962, with daily records not starting until Jan 1966. However, their Mangere site shows a few sub-zero temps in Aug 1965, the lowest being -1.6C on the 5th, with Whenuapai recording -2.1C the same day.

[NZstorm]

I think the term 'subtropical' was meant more metaphorically,

Fair call, Northland's climate certainly has a subtropical flavour.

On the topic of the -3.9C recorded at Auckland Airport I am a sceptic.

[tunster]

I think the term 'subtropical' was meant more metaphorically,

Fair call, Northland's climate certainly has a subtropical flavour.

On the topic of the -3.9C recorded at Auckland Airport I am a sceptic.

I think, like you said, that nowhere in NZ qualifies as subtropical based on Koeppen definitions. The limiting factor is that nowhere has consistently warm enough summers. From memory, a 22C mean is required in the warmest month, which actually makes Sydney borderline.
It's pretty arbitrary though. Northland does look and feel subtropical - whatever that really means
Perhaps it could be defined by synoptic patterns, that is dominance of the subtropical ridge, which on average does spend a lot of the year in the vicinity of Northland.

[spwill]

Northern NZ has humid Summers and mild Winters but does fall short of the koppen definition of sub tropical, however Koppen puts Auckland with the likes of London, Vancouver, Melbourne and Copenhagen.


July so far in Auckland has been well below average on temperature due to night cooling, but dry sunny days to start July.

[NZstorm]

On the topic of subtropical,

A chart here that defines subtropical as inside latitude 35deg. That is not an unreasonable definition.

[spwill]

Niwa description for northern NZ climate.
https://www.niwa.co.nz/education-and-tr ... /map_north

[tunster]

On the topic of subtropical,

A chart here that defines subtropical as inside latitude 35deg. That is not an unreasonable definition.

It's a good starting point but is overly simplistic. You can't even do that for "tropical" climates, because you have plenty of outlier such as Miami which is considered tropical (just) despite being at 25N and Hong Kong which is really not tropical (the winters are far too cold) despite lying inside the geographical tropics.
18C mean temperature in the coldest month is one tropical definition. It seems reasonable enough, as it excludes southern China and much of Taiwan but does include the Florida Keys. i.e. it excludes places that are too cold in winter quite effectively.
Perhaps something similar could be done for the subtropics? Like a mean of 15C in the coldest month? Or some other value? In the end it's fairly arbitrary, and it depends on what you want to weight more - coldness of the winter or hotness of the summer? NZ would do fine on the first, but lose out on the second.

[spwill]

Latitude is just one of the controls on climate but it is a big one.

Atlanta, Georgia, USA 33N has a koppen classification of humid subtropical. However Atlanta has a frosty Winter, the mean temperature in January is 6.1C. The city can get light snowfalls or ice storms but these are uncommon.
Summers are hot, average July temperature is 26C.

[NZstorm]

Auckland had a slightly subtropical summer this year with the mean temp over 4 months Dec-Mar of 20.2C.

If we got that every year then maybe i might agree on the north being a subtropical climate.

[spwill]

I think dewpoint temperature/humidity has to be a factor in subtropical climate.
The Trewartha koppen climate classification allows for cooler subtropical where the mean temperature of the warmest month is below 22C.

[NZstorm]

Auckland-now-a-subtropical-climate accordng to Jim Salinger in 2011.


http://www.stuff.co.nz/auckland/blogs/w ... al-climate

[Nev]

Auckland-now-a-subtropical-climate accordng to Jim Salinger in 2011.

http://www.stuff.co.nz/auckland/blogs/w ... al-climate

Also from 2011 is this interesting article about the length of Auckland's seasons:

'Auckland autumn: Wind changes and mushrooms' - Pacific Media Centre

NIWA's then Principal Climate Scientist, Dr James Renwick appears to contradict what's on their website when asked, is Auckland and Northland subtropical?…

Northland is not quite subtropical. Winter is too much like winter. But wait another 50 years and we might be in business.