RW – thank you for your comments. I agree that any extreme readings should be taken with a degree of scepticism, especially when there has been a change in measuring equipment and that change appears to accompany a change in long term values.

Of course, there are three possibilities.

1. The reading is correct
2. The old equipment was incorrect
3. The new equipment is incorrect

At the moment all we can do is assume the reading is correct relying on those in charge of preparing and calibrating the equipment to have done their job. It was certainly an incredibly sunny month in New Plymouth – there was only one genuinely cloudy day. This is borne out by the the MetService forecasts – based on the ununsual weather systems in place they forecast sunshine almost every day. Simply based on an analysis of those forecasts you would conclude it was a record breaking month – and that is continuing at the moment – wall to wall sunshine today. Look at our current 10 day forecast. Based on that it is likely we will have high levels of sunshine in March as well.

New Plymouth has had very unusual weather and that level of sunshine is certainly possible (and yes it was Perth-like with regard to sunshine – not in temperature though!) By the way I am still curious about whether 330.4 hours in February in New Plymouth beats Blenheims 231 hours in July as a record percentage of what’s possible – you didn’t actually answer that question – and I’m not sure how to work it out.

The next most obvious possibility is that the old equipment was incorrect and that we are now measuring the correct amount of sunshine on properly calibrated equipment. If so – we may have to readjust our perceptions about sunshine levels in various parts of the country. To me the possibility of the old equipment being incorrect is more likely than the third possibility that the new equipment is incorrect.

I have no way of actually knowing which of those three possibilities has actually happened. However as I said at the beginning the 330.4 hours in February in New Plymouth is an official reading (which ties in with the observation that it has been very, very sunny) and for now we have to assume it is correct.

John Haylock’s comment is very interesting. However, I am sceptical of the extremely high values New Plymouth has been getting since “going EWS”. It is a matter of record that a large number of NZ sites have shown very significant increases in sunshine values post-conversion, regardless of the weather conditions prevailing, and almost every month new “highs” are being reported – but almost exclusively at EWSs. I would respectfully suggest that New Plymouth would have been capable of recording 80-84% of the possible sunshine during a remarkable February – which is as high as any place in NZ has ever managed. This would result in a total of about 305-310 hours – still high enough to beat NZ’s leap February record! – but 330 is just not credible to me – that’s getting into Perth territory. BTW, to get 400 hours in Dec or January, even in more southern places, would be more akin to about 87% of possible – I don’t accept that could happen with our current climatology.

For the record, the highest % of possible recprded at a NZ site with good exposure was the 84% at Blenheim in July 1952, when it recorded a remarkable 231 hours.

I’m not picking on New Plymouth here, as the following should make clear. There are NZ stations where the conversions have been consistent with older values – these include Kaitaia, Dargaville, North Shore (probably – but only after a scale-down adjustment), Mangere, Hamilton, Dannevirke, Gisborne (again after some fiddling I suspect), Takaka, Blenheim, Mt Cook, Akaroa (probably), Tekapo (marginal), Dunedin (marginal). But then there are the “offenders” – the worst is lower on the sun scale – Balclutha is getting 300-400 hours more than its manual site ever did, and is completley lacking in credibility. Others, all with large increases, include Greymouth, Hokitika, Ashburton, Te Kuiti, Ohakune, Cheviot, Rangiora and Paraparaumu – this latter is in my region and it just ain’t that sunny – both manual and EWS are still going and there’s a big discrepancy. Then of course there’s the case of table-topper Whakatane – still phony in my view. You don’t turn a 100-150 hour deficit relative to Nelson & Blenheim, maintained over 4 decades or so, into parity or even surplus with no climatological reason to support it! I think NIWA needs to look at instrument adjustments but this would not be a small task and I’m not holding my breath.

The EWS conversion in the UK – which has a lot of climatological expertise – has been a vexed business and is still not really resolved. I have an email I solicited from Philip Eden, an acknowledged expert, on the whole issue.

Just to show I am not just picking on EWS readings – the manual equipment at Invercargill has been reporting anomalously high values – with no occurrence of lowered rainfall or the like for correlative value – for about 15 years. I simply don’t trust the readings, which even average about 100 more hours than those at its EWS.

There’s an Australian who is obsessed with NZ rainfall and sun stats, who posts on an overseas forum. He simultaneously thinks the In’gill figures are OK, but has turned his intellectual???! searchlight on New Plymouth’s readings. He’s bound to write to NIWA. But in fact he doesn’t understand NZ climatologies at all.

I think the Metservice might be having trouble with the thermometer in Oamaru. Here’s today’s noon recordings:

Oamaru Town

at Noon Tuesday 5 Mar 2013
•Temperature: 45°C
•Wind Speed: 7km/h
•Wind Direction: E
•Rainfall (last hr): 0.0mm
•Humidity: 64%
•Pressure: n/a

Check out http://www.metservice.com/towns-cities/oamaru
On 53.4 degrees C at 12.24pm!!!