So here is the app round up for Heathrow:

MetOffice: 38C
iPhone: 36C
BBC: 35C

Both iPhone and BBC have gone up a degree in the last 24hrs.

Something is afoot. If we can get a top four position I’d be happy. But right now I’m reserving judgement on the all time record until we see Arome come into range.

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I'm  not sure why the metoffice dismiss the otherwise accepted high of 38C (100f) at Greenwich back in 1911.  

Non-standard thermometer screening, according to Trevor Harley:

 

"There was a remarkable hot spell, although it is quite difficult to be certain about the exact temperatures, because of (a) uncertainty about screening, and (b) temperatures were taken in F rather than C. The reading of 38.1C - 100.5F - claimed at Greenwich on the 22nd is now not accepted, as the screening conditions at Greenwich were nonstandard; it is more likely to have been about 36.1C - still quite a temperature, and the record for July (until 2006). 97F (36.1C) was also recorded at Epsom, favoured because there was shelter from the light southerly breeze."

https://www.trevorharley.com/1911.html

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Actually that wasd for 22nd July. The Monthly Weather Report says the temperature was higher on August 9 1911, with 98F at Canterbury, Epsom and Raunds, 99F at Isleworth, and 100F at the Royal Observatory, Greenwich.

Even if Greenwich was discounted I am not sure why Isleworth wasn't counted.

See page 81 here: https://digital.nmla.metoffice.gov.uk/digitalFile_1f3ce836-7850-4c40-bce8-0a0ce05baacf/ and the tables on following pages.

Further info here: https://rmets.onlinelibrary.wiley.com/doi/full/10.1002/wea.818

"A temperature of 100°F (37.8°C) was recorded at Greenwich, London, on 9 August 1911, the highest recorded there since observations began in 1841. However, this was from a Glaisher stand, not a Stevenson screen, and it is not accepted as an official record"

Note:  The Glaisher stand was brought into use at Greenwich Observatory in 1841. It comprised a vertical board on which thermometers could be mounted, which could be rotated around a central pivot to face away from the sun. It was reliant on the observer turning the stand regularly. Laing (1977) compared temperatures from Glaisher stands and Stevenson screens and found differences of up to several degrees Celsius on warm sunny days due to the Glaisher stand's design. The Stevenson screen was invented in 1863.

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Kew and Heathrow now down to 37C on the Met Office.

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Might get 22 C as a peak in Edinburgh on Friday!

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I think the cloud will break, especially the further east you are.

Temps have certainly shot up today here - not surprised that Mildenhall is reporting 28. Bit of mid-level cloud making the sunshine a bit hazy from time to time.

East is definitely best today - 28C in Norfolk and Suffolk but only 22C here 35 miles to the west of London.

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East is definitely best today - 28C in Norfolk and Suffolk but only 22C here 35 miles to the west of London.

Hopefully the cloud on the front will break tomorrow. It is quite a patchy front in terms of rainfall which gives me hope.

Kew and Heathrow now down to 37C on the Met Office.

Its back up to 38C in Heathrow 

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Dodgy exposure, and it’s a lot higher than most surrounding stations. Then again, Gravesend was often much higher than other local stations.

The same to with Heathrow or even down here. Often either Thorney or (rarely both together) Solent (now gosport fleetland) would be higher then surrounding areas. 

 

Non-standard thermometer screening, according to Trevor Harley:

 

"There was a remarkable hot spell, although it is quite difficult to be certain about the exact temperatures, because of (a) uncertainty about screening, and (b) temperatures were taken in F rather than C. The reading of 38.1C - 100.5F - claimed at Greenwich on the 22nd is now not accepted, as the screening conditions at Greenwich were nonstandard; it is more likely to have been about 36.1C - still quite a temperature, and the record for July (until 2006). 97F (36.1C) was also recorded at Epsom, favoured because there was shelter from the light southerly breeze."

https://www.trevorharley.com/1911.html

It was a metoffice recording still. A little while back i was actually reading of it on metoffice website in their historical section.

 

Non-standard thermometer screening, according to Trevor Harley:

 

"There was a remarkable hot spell, although it is quite difficult to be certain about the exact temperatures, because of (a) uncertainty about screening, and (b) temperatures were taken in F rather than C. The reading of 38.1C - 100.5F - claimed at Greenwich on the 22nd is now not accepted, as the screening conditions at Greenwich were nonstandard; it is more likely to have been about 36.1C - still quite a temperature, and the record for July (until 2006). 97F (36.1C) was also recorded at Epsom, favoured because there was shelter from the light southerly breeze."

https://www.trevorharley.com/1911.html

Anyone else find it remarkable that it was the same date in 1868, and the same temperature to the degree F, quoted as an old record for Tonbridge? Also discounted.

Lack of reliable apparatus means the potential for a 40°C max on 'Hot Wednesday' (July 1808) is under-researched.

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It was a metoffice recording still. A little while back i was actually reading of it on metoffice website in their historical section.

Yes I put a link to the Monthly Weather Report on the previous page. I need to explore the archives on that site - looks like there is loads of good stuff.

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I find it odd that despite 38C on the Met automated temperature for Heathrow all the surrounding towns are being forecasted in the 32C-33C range.. places like Slough, Hayes, Hounslow, Stanwell, etc. To me this really highlights the anomaly Heathrow is.

I find it odd that despite 38C on the Met automated temperature for Heathrow all the surrounding towns are being forecasted in the 32C-33C range.. places like Slough, Hayes, Hounslow, Stanwell, etc. To me this really highlights the anomaly Heathrow is.

In reality most days where Heathrow is the hottest location (and it’s not actually as common as you might think, even when London is the warmest region) the nearby sites of Northolt, St James Park, Kew, Wisley - and sometimes down to Charlwood- are there or thereabouts. I am pretty sure this is human intervention by the Met Office. I think when most apps search “London” they get Heathrow. 

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I find it odd that despite 38C on the Met automated temperature for Heathrow all the surrounding towns are being forecasted in the 32C-33C range.. places like Slough, Hayes, Hounslow, Stanwell, etc. To me this really highlights the anomaly Heathrow is.

My point exactly on the date record thread. Qu (me):

This is very interesting because, as you say, 38 is forecast for Heathrow, and also for Kew, with 37 for Northolt.

 

Yet other locations in the area are forecast to be 5 or more degrees lower- for example, Wembley, Twickenham, Richmond, Kingston, Chertsey and London only 33; Staines 32. 

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I find it odd that despite 38C on the Met automated temperature for Heathrow all the surrounding towns are being forecasted in the 32C-33C range.. places like Slough, Hayes, Hounslow, Stanwell, etc. To me this really highlights the anomaly Heathrow is.

Yet Northolt is showing 37.

 

In reality most days where Heathrow is the hottest location (and it’s not actually as common as you might think, even when London is the warmest region) the nearby sites of Northolt, St James Park, Kew, Wisley - and sometimes down to Charlwood- are there or thereabouts. I am pretty sure this is human intervention by the Met Office. I think when most apps search “London” they get Heathrow. 

on the contrary it is often one of the UK hotpots.. I did something recently i checked the metoffice twitter page for the UK hotpots and Heathrow was very frequently one of them. I checked around 20 days i think it was and Heathrow was 7/8  times the national hot spot.  

 

My point exactly on the date record thread. Qu (me):

This is very interesting because, as you say, 38 is forecast for Heathrow, and also for Kew, with 37 for Northolt.

 

Yet other locations in the area are forecast to be 5 or more degrees lower- for example, Wembley, Twickenham, Richmond, Kingston, Chertsey and London only 33; Staines 32. 

All three locations are often hot spots and are all located within close proximity of each other. Perhaps a combination of urbanisation & local terrain play a part? The heat equivalents to say Braemar & Altnaharra are for cold? 

 

All three locations are often hot spots and are all located within close proximity of each other. Perhaps a combination of urbanisation & local terrain play a part? The heat equivalents to say Braemar & Altnaharra are for cold? 

They do well with Southerly or SSE winds or calm (though St James park often wins in dead calm), my local one London City airport is good in Westerlies but not if there’s any Easterly component to the flow 

I would say there is a long standing UHI influence at Heathrow, Northolt, St JP, Gatwick, City airport, the old Gravesend Broadness and possibly Kew although given how localised UHIs are and how much green is around Kew that one is more questionable. On the UHI maps from peak nights the strongest impact is in zone 1 central London, although St James park is a relatively cool island because of the string of parks in the area. UHI is overwhelmingly a night phenomenon but there are measurable daytime effects in mid latitude cities like London.

Topographically they are definitely hotspots as they are very low altitude, practically sea level, and sheltered by the downs but without being coastal. Gloucestershire airport is another one with similar topography in the West Country.

The other hotspot which annoyingly has no local weather station is the Medway valley north of Maidstone. On reanalysis maps always very hot as it’s at or close to sea level, sheltered to the South, West and East and close to but not right by the Thames Estuary. It’s where Chapel Down have their award winning Kits Coty vineyard which is just about the hottest in the country alongside the Crouch Valley vineyards in Essex.

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MetOffice app now only showing 37C

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