August 2017 in Central England was rather a cool affair, which would have been even cooler, if it hadn’t been for some warmer values in the last 10 days of the month. I made the mean temperature 15.6°C which gave it an anomaly of -0.8°C using the 1981-2010 long-term average (fig 1). This was the first below average month in Central England since January, nine of the last thirteen August’s have been cooler than average (fig 2).
The Met Office finally got there act together today, and fixed their web service and updated their CET web page with the latest data. As expected, March 2017 was a very mild month, and when the temperatures were finally confirmed today, it turned out that it had been the 3rd mildest since the monthly series started in 1659. I make the mean temperature for the month 8.68°C, which was exactly 3°C above the 1961-1990 long-term average. It couldn’t quite beat the CET of either March 1938 or 1957, so it ended up being the warmest March since 2012.
The month saw four new high minimum temperature records set and one highest maximum record on the 30th.
2016 in the CET series looks to have been the 18th warmest year since the monthly series began in 1659. It was according to my statistics just +0.02°C warmer than last year. That makes it that 12 of the last 20 years have occurred in the last 20 years, if my eyesight is to be trusted. The mean temperature of 10.33°C was +0.85°C above the 1961-1990 long-term average.
Quite a number of new day maximum records (the eleven red stars in fig 2) were broken in 2016, including the one for Christmas day. Nine new high minimum records were also set (blue diamonds (todo: change colour to red)). Only one new minimum record was set during the year for the 28th of April (blue star). The two lower charts (fig 2) show you the warm and cold spells that occurred during the year, and as you can see the whole year was dominated by warm spells, some of them occasionally very long although it’s difficult to see when viewing an entire year.
This annual heat map (fig 3) makes it very easy to visualise the annual CET anomalies of the last 357 years at a glance.
December 2016 can be summed up as a generally mild month where the daily CET value alternated between distinct periods of very mild and brief colder spells, especially at the start and end of the month, with a record warm Christmas day thrown in to boot just for good measure. Overall the final anomaly of +1.3°C for the month, will be forever dwarfed by the massive +5.0°C of the previous year!
It’s been a very warm start to the first 13 days of September 2016 in the Central England Temperature [CET] daily series. Using provisional data it lies 10th warmest for the first 13 days in the daily mean series 1772 with a mean anomaly of +2.83°C, warmer than even the great September of 1959.
If you rank on daily maximum temperatures which dates back to 1878 rather than 1772, then 1959 is out at number one, with 2016 trailing by 2.26°C. The reason why September 1959 was so warm was that it was anticyclonic and very sunny.
Interestingly, September 1906 – the year with the highest September temperature – appears prominently in both tables.
It looks like Summer 2016 was the warmest in Central England since 2006 with a mean temperature of 16.43°C which was +1.08°C above the long-term average (1961-1990). Surprisingly no maximum records were broken during the summer but two high minima were.
In the bigger scheme of things Summer 2016 was the joint 27th warmest since 1659 based on mean temperature.
Here is a table and chart that display the daily extremes in the Central England Temperature [CET] series from 1878. When I say daily extreme, what I mean is the difference between the highest and lowest temperatures that have occurred on that particular day since 1878. It was a little surprising when I added a best fit curve and noticed that it wasn’t as seasonal as I would have thought, with the highest extremes in the summer and the lowest in the winter. Instead the lowest extremes seem to occur in November with the highest extremes in May and June. It does of course depend on what kind of best fit curve you employ, the one I used in this graph were to the 5th polynomial according to my charting component, which produces a very smooth curve than a higher polynomial would do.
In Central England the mean temperature of the Summer [JJA] so far is 1°C above the long-term average, which currently makes it the 17th warmest of the last 138 summers for the period from 1 June to 22 July. So pretty warm, but not in the same league as 1976 or 2003 for the same time, but of course there is still almost six weeks left to run of the meteorological summer and August might be a sizzler! Below is a chart comparing maximum temperatures of 2016 with the summer of 1976 forty years before, of course the data for July is still provisional but there’s still no missing the recent hot day of Tuesday the 19th. The way the anomalies for this summer are currently (maximum +0.71°C minimum +1.35°C) it points to warm nights being the main driver rather than warm days, in fact maximums ran below average for much of the period between the 24th of June and 15th of July.
The June Central England Temperature [CET] values are now in, and I make the mean temperature for the month around 15.3°C with an anomaly of +1.08°C (wrt 1961-1990 LTA). June 2016 was warm for the first 10 days or so, but temperatures returned to near average for the remainder of the month as the westerlies returned, and it ended up being the #46 warmest in the monthly series back to 1659. One thing I did notice through June was the preponderance of warm nights.