It ain't half hot mum

[xmetman]

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 in both tables.

[Len Wood]

It's the min temperature anomaly that looks a bit special.
Could it be the humid air reduced the radiational cooling at night?
Or advection, where there was a continuous feed of warm continental air at night,
which was not so evident in other years.

Len
Wembury

[xmetman]

Len

A combination of warm sunny days and cool nights with maximum radiation cooling. The maximums are way above the norm and the minimums similar although not quite as extreme. The mean temperature would be misleading in a way because the warming is almost cancelled out by the cooling, so that when you judge 1959 on its mean temperature its very average, when we know only too well that it was anything but!

Bruce

[Len Wood]

I was looking at +3.21 degC for this Sep 2016.
It ranks top for min anomaly.

[xmetman]

Len

Yes its yet another warm month as regards minimum temperatures with exceptionally warm nights so far this September. We've.already broken one highest mininum date record marked by a blue diamond on this chart. The horizontal rad bars sub chart shows the warm spells for max/mean/min temperatures in the last 3 months.

Bruce.

[Scott Whitehead]

Bruce: that's really interesting - 1959 must have been a classic 'seasonal mists and mellow fruitfulness' month that we seem to see rarely now. But perhaps it is the maxima that most people notice by September?

[xmetman]

Yes highest usually does make headlines. 

September 2016 has now jumped to #4 warmest on 14 days worth of daily CET. 

Last really warm day today, so it now depends on what turns up in the second half of the month.