Is Oxford Getting Wetter?

By Paul Homewood

 

 

 

The Radcliffe Meteorological Station, at the University of Oxford, claims to possess the longest series of temperature and rainfall records for one site in Britain. The station has kept continuous daily records since 1815, with irregular ones before that starting in 1767.

Oxford, of course, has been at the heart of some the most excessive rainfall this winter.

Oddly, though, the Met Office database only has records back to 1853. Using this, let’s take a look at the monthly precipitation trends, presented as a 120-Month Running Average.

 

 

Figure 1

http://www.metoffice.gov.uk/pub/data/weather/uk/climate/stationdata/oxforddata.txt

 

• The red line is the trend (and not the mean). It is, to all intents and purposes, flat.
• There are peaks and troughs, but the current level is not out of line with many earlier periods.
• The wettest period was during the 1870’s and 80’s.

 

We can also analyse the wettest months. Figure 2 shows the distribution of the Top 50 wettest months.

 

Figure 2

• There appears to be a certain amount of clustering at various times, but again there is little sign of anything unusual in the last decade or so.
• The wettest month of all was October 1875, when 192.9mm fell.
• There have been various claims made about last month’s rainfall of 146.9mm, but in fact it only ranks the 15th wettest since 1853. In other words, typically a once a decade event.
• The wettest month in the last decade was June 2012, which registered 151.7mm, but this still only ranks as 9th wettest.
• The five wettest months were all prior to 1950.

 

Last year I also took a look at the wettest days at Oxford. The Met Office daily data was only available from 1931, so consequently misses out many of the wetter periods identified above. Also, as I did the exercise last year, the data finished at the end of 2012, (which you may recall was a rather wet year!).

(The data is not publically available, but was sent to me by the Met Office).

 

Figure 3

 

Again, some clustering is noticeable, but the really heavy rainfall days were in the 1950’s and 60’s. It would have been interesting to see what the picture would have looked like in earlier wet periods.

 

Summary

We keep hearing claims that global warming is leading to more intense rainfall, but what this exercise certainly does show is that there is absolutely no evidence of this happening in Oxford, either in daily or monthly amounts.

Indeed, quite the reverse – heavier rainfall seems to have been more prevalent in earlier, cooler times.

 

One final comment. On the Met Office record, 2012 was the wettest year at 985mm. However, the Radcliffe website gives a figure of 1034mm for 1852, which just happens to be the year before the Met Office start their database.

Strange!