General January Weather

[Nev]

Here's NIWA's, January 2019 National Climate Summary.

The national average temp of 18.8C was 1.7C above normal, making it NZ’s 3rd warmest January on record after 2018 (20.3C) and 1956 (19.0C).

The month's highest temp of 38.4C was recorded at Hanmer Forest on the 31st, and the lowest temp of -0.3C was recorded at Manapouri on the 12th.


Note that NIWA are still claiming that Ruakura, Hamilton's 32.9C on the 29th is its highest all-time daily temp since records began in 1909, which should include those earlier higher temps of 34.7C in Dec 1935, 33.3C in Feb 1928 and 33.1C in Feb 1935...?

Also note that NIWA appear to be using Akld Aero's mean-temp and rainfall for its Akld main centre, even though it says Mangere.

[cbm]

Note that NIWA are still claiming that Ruakura, Hamilton's 32.9C on the 29th is its highest all-time daily temp since records began in 1909, which should include those earlier higher temps of 34.7C in Dec 1935, 33.3C in Feb 1928 and 33.1C in Feb 1935...?

Yeah, I've mentioned those higher temperatures in 1930's every time when talking about last Tuesday's high. They are right there in their own database. Its true that the station has changed a couple of times, first in 1997 then 2005 (with a bit of transition overlap). I can't imagine that they don't know about those readings from the 20's and 30's. So it's like they know something we don't?

[Nev]

Note that NIWA are still claiming that Ruakura, Hamilton's 32.9C on the 29th is its highest all-time daily temp since records began in 1909, which should include those earlier higher temps of 34.7C in Dec 1935, 33.3C in Feb 1928 and 33.1C in Feb 1935...?

Yeah, I've mentioned those higher temperatures in 1930's every time when talking about last Tuesday's high. They are right there in their own database. Its true that the station has changed a couple of times, first in 1997 then 2005 (with a bit of transition overlap). I can't imagine that they don't know about those readings from the 20's and 30's. So it's like they know something we don't?

Yes, my comment 'those earlier higher temps' was in reference to your earlier posts.

I think that someone initially probably only checked 2 of the 3 sets of records and that error has been repeatedly left unchecked. Note that the authors of NIWA's monthly reports seem to change as often as the seasons these days.

Also note that the first set of records, which relate to early manual readings, and the second set, which are for automated readings, were both taken taken from within the same enclosure. The third set and current site, about 600-700 metres to the NW, was established in late 2005 because land on the old site was to be sold.

I'd also imagine that Hamilton's urban sprawl (along with its Urban Heat Island effect) has been gradually creeping east to the point that it's now right on Ruakura's doorstep, which is probably why Hamilton Aero is favoured as NIWA's main-centre site.

[Simon Culling]

A tweet from NIWA that might be of interest, Rupert, concerning 355 hours of sunshine in January at both Richmond (Nelson) and Appleby. Not bad totals - we would love to see that in June/July in the UK.

https://twitter.com/NiwaWeather/status/ ... 5875387393

[RWood]

A tweet from NIWA that might be of interest, Rupert, concerning 355 hours of sunshine in January at both Richmond (Nelson) and Appleby. Not bad totals - we would love to see that in June/July in the UK.

https://twitter.com/NiwaWeather/status/ ... 5875387393

Yes Simon, even allowing for electronic-manual differences, they are pretty good totals. The highest totals on record in the manual Campbell-Stokes data are 336 at Nelson city (Dec 1934), and 335 at both Blenheim (Jan 1957) and Taupo (Jan 1950). I think these would equate roughly to the 355-hour electronic readings.

Interestingly though, the record highest percentages of possible (manual records) occurred in a winter month - July 1952 saw 230.8 hours at Blenheim (84-85 % of possible) and 226.5 hours at Nelson Aero (82-83% of possible). That month saw persistent high pressures over central NZ and very high sunshine readings in eastern districts from Canterbury to Bay of Plenty. In the fickle ways of New Zealand climates, August 1952 featured a lot of easterly flows over the South Island with cloudy conditions in the east (just 139 hours at Blenheim) and high rainfall in North Canterbury, but record low rainfall in Fiordland, Southland and the Otago lakes region.

[cbm]

"I'd also imagine that Hamilton's urban sprawl (along with its Urban Heat Island effect) has been gradually creeping east to the point that it's now right on Ruakura's doorstep, which is probably why Hamilton Aero is favoured as NIWA's main-centre site."

Apart from the new 4 lane road, which I mentioned on the other thread, the area around the Ruakura site has not changed too much since the 1960s/70s . New housing has been sprawling on most other boundaries but not there. What is coming however is Tainui's inland port and that is going to add a huge amount of thermal mass between there and the new expressway to the East. When that's all done it's effect on temperature readings is going to have to be seriously considered.

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