Niall,
Be careful about your thermometer siting argument. You are beginning to sound like Anthony Watts.
Godforbid
I do agree with him of the need to have a robust network of weather stations. But that's about the end of it. For example I understand the need for adjustments to account for changes to a site and/or instrumentation over time. Deniers like Watts get agitated when adjustments are mentioned. They have highlighted the changes and yet at the same time jump up an down whenever anyone mentions adjustments. They can be very manipulative with data, and use it to further their own ends.
I applaud the establishment of USCRN which long term will be the gold standard climate reference in the U.S.
What I don't like is National Meteorological Agencies frequently changing the siting of their stations. Unfortunately this does happen from time to time, usually around the airports. I'd say a lot of people are not aware of this.
Ideally you would like your temperature stations to stay the same - so when extreme cold or heat arrives you can say yes it's the warmest since the station started etc. What made me curious about Rockford cold record was why other Illinois stations didn't break record and yet Rockford seems to have broken a very long term cold record by over 2 degrees C. But I've gone through that one already.
The NWS Chicago also mention a new cold record at Barrington (Ill). Records show that there has been a station at Barrington since 1962 but again there have been many station moves. In 1967 (0.6miles) and 1971 (1.7miles) and 1987 (3miles). The 1987 move was to a lovely site in the Crabtree Nature Center. A nice green area as the older sites had become too industrial. So it would be correct to say it has been coldest in Barrington since 1987. This also backs up Chicago O'Hare - coldest since the 1980s.
I come across this thing quite a lot. News agencies saying coldest ever or warmest in 100 years. But really only applies to how long the site was in existence.
Why do I care about this ?
1) It's what I do. I am a climatological observer. I strive to maintain good standards
2) I don't like fake/imprecise news. It can often be used and manipulated by nefarious people.
This is turning into a longish post and I haven't mentioned Australia. We have seen a lot of heat records from Australia already this year but how do these compare with the standard method of recording temperature by electronic sensors?
The Australian Bureau of Meteorology have for some reason gone out on a limb with their recording of temperature extremes. Unlike most other countries I know, they log the highest 1 second spot temperatures as being the maximum. The correct way should be to take the average of the readings over 1 minute. Reason for taking the 1 minute average is because this correlates closely with the old mercury max readings. And for record purposes we should strive to maintain as close as possible to the historical way. Or else you should correctly say highest since this method was first employed (1st Nov 1996).
BTW this criticism of the Australian BOM only applies to temperature extremes. I have no reason to suspect that the daily, monthly and annual mean temperatures are much different now to the historical liquid-in-glass method.