18.3C (65F) recorded for the 1st of February 1828 at Stratford in London. A remarkable reading for a site that is not affected by the Foehn effect. Makes one wonder just how accurate that reading is?

15.6C (60F) was recorded the previous day (31st January), weather described as rainy night probably in a very mild sector and next day was described as cloudy. 

17.8C (64F) was recorded on the 23rd of January, the pressure reading was 1033mb with a SW, which would indicate a Bartlett SW flow, weather was described as fine and the days immediately before this value was recorded were into double digits.

16.7C (62F) was recorded on the 4th of February, weather was described as fine.

Report from Memel, which is today called Klaipėda  in Lithuania on 5th February, indicates the past forthnight was very mild. Given the distance between London and Lithuania, it looks like most of Europe experienced a very mild spell going from January into February.

Possibly something like this

Interesting. As it was in 1828, that would have well before Stevenson - or even Glaisher - screens, and one wonders what the exposure of the thermometer was like. 

I think we might look back to the 'Tambora' eruption (Augmented by Galunggung?) and look to the resonations across the global climate system that such an impactful event will have driven over the decade following?

Was this London ( and wider?) temp event nothing but a swan song of the trop/strat changes that such a big event('s) set in motion ( constructive and destructive waves?) over a decade before and then reshaped by Galunggung?

I have now taken to looking at the biggest equatorial eruption close before any exceptional weather event folk chose to trawl up so we can better understand the event other than it merely be it being 'Weather'?

With a high V.E.I. and a equatorial position, you can near guarantee the type of short lived peturbations such a lowering of both temp profile ,equator to pole, and incoming solar will drive?

Today we seeing  these events in lieu of these 'associated' volcanic events driving them? 

I suppose as we have lessened the temp profile from pole to equator and , over our messier phases, blocked incoming solar with our Soot/So2 outputs, we ought to expect similar events to those we see dotted through our climate/weather records? 

There is no CET Max or Min for that day in 1828 (these didn't start till 1878) but the CET Mean for that day is only 6.7C

As the weather was described as cloudy this also rules out the possibility of a huge diurnal range such as we had this week

I realise that the CET area does not include London but I am having problems working out what sort of synoptics could lead to both sets of data being accurate

Is there a reference for this event ?

I've just been looking up the CET mean for that day too. Assuming that the original entry would have been handwritten and in Fahrenheit, my guess is that whoever transcribed the data at a later date either misread the value or else - if this was before electronic calculators - made a mistake in the conversion from Fahrenheit to Celsius. It'a a pity that the long-running record for Greenwich only began in 1841, so one can't cross-check against that. The data from the Radcliffe Observatory at Oxford goes back to 1815, but it looks as if the daily data is only available if you pay for it.

On second thoughts, the fact that there were several other high temperatures recorded just before and just after that date makes me think that a problem with the thermometer or the exposure is more likely.

There's a list of the highest maxima recorded for each day of the year here: http://www.torro.org.uk/hightempsyear.php

Geldeston (Norfolk) 1898 and Hodsock Priory (Notts) 1923 both recorded 16.1 on 1st February, but Stratford is not mentioned.

Won't do because it is only offical screen temps. You won't find anyhting before 1860