Met Office Hadley     16.2c.    Anomaly    0.1c.  Provisional to 5th.

Metcheck                 16.56c.  Anomaly    0.33c.

Netweather              17.18c.  Anomaly   0.99c.

Clevedon Weather    16.9c.   Anomaly    0.6c.

Mount Sorrel            17.0c.   Anomaly    0.8c.

My Mean                 17.0c.    Anomaly    0.6c.       

Met  Office  Hadley     16.5c.     Anomaly     0.4c.

Metcheck                   16.50c.   Anomaly     0.27c.

Netweather                17.24c.   Anomaly    1.05c.

Clevedon Weather      16.8c.     Anomaly    0.5c.

Mount Sorrel              17.0c.     Anomaly    0.8c.

My  Mean                   16.9c.     Anomaly   0.6c.

Met Office Hadley         16.2c.       Anomaly       0.2c.     Provisional to 7th.

Metcheck                     16.53c.     Anomaly       0.31c.

Netweather                  17.08c.     Anomaly       0.89c.

Clevedon Weather        16.7c.       Anomaly       0.4c.

My  Mean                     17.1c.      Anomaly       0.4c.

I wonder if after this coming week things will settle right down.

http://www.telegraph.co.uk/news/weather/11791735/UK-weather-Summer-returns-to-Britain-as-Europe-bound-tourists-warned-of-heatwave-conditions.html

You won't get much if you bet on this August being the hottest ever.

Right Down but don't know about settling...

The CET is a happy climber if the 12z GFS op run is close to what we end up with; a rough estimate using raw data lifts the CET to near 17.3*C by 21st August, after which fresher (but still settled - chilly nights) conditions bring it down to the high 16's by 24th.

I'm starting to get the feeling that a late month chill out is going to be required for it to finish cooler than average. Nice to be looking at things from this side during a summer month for a change... particularly August 

Nice post there and very good point.

Met Office Hadley        16.3c.       Anomaly     0.4c.  Provisional to 8th.

Metcheck                    16.75c.     Anomaly     0.52c.

Netweather                 17.24c.     Anomaly     1.05c.

Clevedon Weather       14.3c.       Anomaly     2.0c.

Mount Sorrel               17.2c.       Anomaly     1.0c.

My Mean                     17.4c.       Anomaly     0.1c.

My Annual   11.1c.  Difference   5.4c.  (changed 4 times this month already)        

Met Office Hadley     16.4c.        Anomaly        0.5c.     Provisional to 9th.

Metcheck                 16.99c        Anomaly         0.77c

Netweather              17.36c.       Anomaly         1.17c.

Clevedon Weather    17.0c.         Anomaly         0.7c.

Mount Sorrel            17.4c.         Anomaly         1.2c.

My Mean                  17.4c.         Anomaly         0.1c.

Out of pure interest, I've just started to compare mean values obtained using hourly readings with those obtained using only the max and min values.

Yesterday my location came in at 15.65*C for Max and Min but 15.88*C for the combined Hourly Means.

Meanwhile analysis for Heathrow returns 19.55*C and 19.84*C respectively.

This is not surprising really, given that the hours of heating are considerably longer than those of cooling at this time of year.

Where the hourly method would really come into its own would be on a day where it's cloudy and in the high teens for much of the time but then there's a brief period of sunshine causing a sudden jump in temperatures well into the 20's - taking the hourly means combined would give a more accurate representation of what most people experienced that day than the traditional max + min method.

I may get to test that theory out over the coming few days 

I reckon you would see some of the largest differences between the two methods on days in winter where it's mild and cloudy until a sudden clearance and drop in temperature late in the night. I'll aim to run a short experiment this coming winter should such conditions arise 

Those of us that use the Weatherlink software already have access to this data as it calculates the mean using all available data points for each 24 hour period. I have data points at one minute intervals going back almost 10 years. The differential between the two methods is generally higher in the winter.

Possibly looking rather cool second half to August? CET finish in the 15's, perhaps?

As an example here is my data for 2014. Generally the mean calculated by taking the average of the maximum and minimum gives a higher figure than the mean of all data points during the day. That is not always the case - especially in winter -e.g. if you have a sudden clearance of cloud just before dawn which pushes the minimum right down. Then the simple max / min average will be lower.

Often the differences are actually very small. Sometimes though the differences can be substantial as evidenced by March and September in 2014.

The size of the difference does not appear to be impacted by the absolute diurnal variation in temperature. It will be down generally to more subtle factors in most cases which are hard to pin down to specifics.

The Met Office site where we all look up these daily CET figures also contains this rather cryptic comment:

Note that the estimated mean value may not be equal to (max+min)/2 because there is always one more minimum
value than maximum. This discrepancy is exaggerated during the first part of the month and when the nights have
suddenly become significantly colder or warmer.  

I don't know what time of day these daily readings are done but I am assuming this means that (say) if a "day" runs from 6AM to 6AM then one very cold night in a run of generally mild nights might supply the minimum value for 2 days as it could be the coldest at both 5.59AM and 6.01AM

Is this what it means or am I just talking boll**cks here

Bit Late in the day after my wanderings but here are some CET.

Met Office Hadley       16.6c.    Anomaly      0.7c.

Metcheck                   16.98c.  Anomaly      0.76c.

Netweather                17.48c.  Anomaly      1.29c.

Clevedon Weather       16.9c.   Anomaly       0.6c.

Mount Sorrel               17.4c.   Anomaly      1.2c.

My Mean                    17.04c.  Anomaly      0.1c.  

I think the cross over is 09:00.

It probably just about makes up for the fact that  the Min/Max/2 method, as shown by GW above, appears to give an average  diff of about 0.14C each month (higher) so without the effect it would be even worse.l

It looks like swings and roundabouts.

Here is the latest CET update. Despite some cooler conditions over the weekend it should return to average next week. For now it looks like the CET will hold up just above 16C.

The question is will 2015 join 2007 and 2011 in not seeing any month with an overall CET of 16C or more? Seems strange saying that about 2011 given it was a very warm year overall.

I think it is more straightforward than that. When they post the updates each morning there will by definition always be one more minimum reading for the month relative to maximum readings. If you averaged all those figures you would get a distorted mean.

Take today for example. The Hadley update this morning provided maximum readings for August up to the 10th. However, minimum readings are available up to the 11th. This is because the readings are taken for a 24hr period to 09z and the maximum for that period is assigned to the previous day (the 10th in this case) whereas the minimum is assigned to the current day (the 11th). So currently we have 10 maximum data points for August and 11 minimums.

Aha I see - thanks GW. That all washes out after the end of that month as the number of maxes and mins becomes the same

I think I'm g;ad the same night's data could not end up being allocated to more than 1 date as that would have artificially skewed the monthly average I think

Thanks for the update GW. Am starting to feel relatively comfortable with my guess, though it's still early days!

Met Office Hadley       16.5c.       Anomaly        0.5c.   Provisional to   11th.

Metcheck                   16.86c.     Anomaly        0.64c.

Netweather                17.33c.     Anomaly        1.14c.

Clevedon Weather       16.9c.      Anomaly         0.6c.

Mount Sorrel               17.2c.      Anomaly         1.0c.

My Mean                     17.1c.     Anomaly          0.4c.   

Met Office Hadley       16.5c.      Anomaly       0.5c.     Provisional to  12th.

Metcheck                   16.91c.    Anomaly       0.69c.

Netweather               17.34c.     Anomaly       1.15c.

Clevedon Weather      16.7c.      Anomaly       0.4c.

Mount Sorrel              17.3c.      Anomaly       1.1c.

My Mean                    17.2c       Anomaly       0.3c.    

Met Office Hadley          16.5c.       Anomaly        0.4c.   Provisional to 13th.

Metcheck                      16.90c.     Anomaly        0.68c.

Netweather                   17.32c.     Anomaly        1.13c.

Clevedon Weather          16.5c.      Anomaly        0.2c.

Mount   Sorrel                17.2c.      Anomaly        1.0c.

My     Mean                    17.1c.      Anomaly       -0.4c.  

CET currently at 16.36C by my calculations. The weekend looks quite cool mainly due to cold nights.

Next week temperatures should be slightly above average. This is mainly due to warmer nights returning though. Daytime maximums will only be close to average.

Currently estimating 16.14C by the 28th. So I suspect we will finish close to the July CET of 15.9C, possibly a little higher.