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The Heathrow Tarmac Strikes Again!

June 23, 2017

By Paul Homewood



As we know, the Met Office have informed us that Wednesday was the hottest June day since 1976, with a temperature of 34.5C recorded next to the runway at Heathrow.

Apparently the previous hottest June day since 1976 was at Worcester in 1995, with 33.8C set.


This is all very interesting, because I asked the Met Office what the highest temperature was on Wednesday after the Heathrow figure.

This was their reply:



So the next highest temperatures, set at Kew and Northolt which are both close to Heathrow, were 33.8C, the same as in 1995.

Only by using the Heathrow temperature were the Met Office able to claim the “hottest day since 1976”.


Many readers will recall similar shenanigans in 2015, when the tarmac at Heathrow conveniently allowed the Met Office to claim the hottest July day on record.

  1. Jack Broughton permalink
    June 23, 2017 10:20 am

    Perhaps following Chaamjamal’s recent posting the AGW believers should be looking at the hottest night on record rather than the hottest day.

    Fortunately they do not read heretical web-sites like this or I would not dare suggest this!

  2. Chris Lynch permalink
    June 23, 2017 10:21 am

    When I heard that a five day heatwave was forecast for England I just knew that the met office would claim some record or other and that the location would be the tarmac at Heathrow. Kudos to you for pointing out the nature of the Emperor’s new clothes as usual.

  3. June 23, 2017 10:22 am

    This tells us more about the Met Office in 2017 than it does about the British weather.

  4. June 23, 2017 10:33 am

    The Met Office is either staffed with idiots or con men with a hidden agenda. Who in their right mind would claim that London temperatures were the same as one thermometer next to a runway of one of the world’s busiest airports?

  5. June 23, 2017 10:35 am

    On the other hand…France marked its hottest June day since World War II on Wednesday.

  6. June 23, 2017 10:52 am

    I flew into Heathrow on June 13, 2015 for Magna Carta and out a week later. It was certainly not uncomfortably hot. I wore a suit for Runnymede on June 15 and for the tea later down the road at Lady Fairhaven’s.

  7. NeilC permalink
    June 23, 2017 10:59 am

    ICAO DD/HHMM Vis Pressure Temp DP RH Wind Dir Wind Speed
    EGLL 21/1750 6.2 1011.0 32.0 16.0 38 200 11
    EGLL 21/1720 6.2 1011.0 33.0 15.0 34 190 10
    EGLL 21/1650 6.2 1011.0 33.0 14.0 32 200 10
    EGLL 21/1620 6.2 1012.0 34.0 14.0 30 210 10
    EGLL 21/1550 6.2 1012.0 33.0 15.0 34 180 9
    EGLL 21/1520 6.2 1012.0 34.0 14.0 30 170 9
    EGLL 21/1450 6.2 1012.0 34.0 14.0 30 160 10
    EGLL 21/1420 6.2 1013.0 33.0 15.0 34 160 10
    EGLL 21/1350 6.2 1013.0 33.0 15.0 34 160 7
    EGLL 21/1320 6.2 1013.0 33.0 16.0 36 170 8
    EGLL 21/1250 6.2 1014.0 32.0 16.0 38 160 7

    This is an extract from METARS for Heathrow.

    The max temp would have been taken from the Max Thermometer, not the observation readings. However, notice the wind direction. With the screen on the north side of the 09L runway, the heat from not only aircraft using 09L but from virtually the whole infrastructure of Heathrow would have influenced the readings.

  8. David Pope permalink
    June 23, 2017 11:24 am

    I did 2 weeks ‘practical’ training at the Heathrow Met Office when gaining my met observers certification wayyy back in the late 1970’s and was astounded at the time that the office & equipment were so close to the runway. So close that you couldn’t go outside if Concorde was departing that runway ~ still a truly wonderful sight.
    Just for info, unless it’s changed in the interim, if the dry bulb temperature read an odd number + 5 then the reported figure was rounded down, i.e. 33.5 would be reported as 33 whilst even numbers were rounded up, 34.5 reported as 35.
    Incidentally, when I was taught met, cloud was reported in oktas, giving a pretty good idea of what amount of the sky was covered with what type of cloud. In the interim, there’s been a lot of what I call ‘dumbing down’ of such data, as it’s now reported as something along the lines of ‘few’ ‘scattered’ ‘broken’ & ‘overcast’. Apparently it became too difficult to work in oktas of cloud…………but as long as you know how many oktas of cover ‘few’ etc are then you’re home & dry (or not as the case may be). But wait ~ in that case, why not just report in eighths? After all, it worked well enough for long enough. Answers on a postcard please 😉

    • NeilC permalink
      June 23, 2017 2:45 pm

      As far as I remember the rounding of temperatures was; if a temp of 33.5 it would be rounded to the odd number hence 33 but a temperture of 34.5 would have been round to 35. But my memory might not be so good nowadays.

      • David Pope permalink
        June 23, 2017 4:48 pm

        Thanks ~ I think that’s probably finger trouble on my part. It’s been more than a few years since I ‘officially’ observed. Ah, the good old Meteorological Slide Rule Mk VI A.
        Happy days.😁☀️🌧🌩

  9. Ian Johnson. permalink
    June 23, 2017 12:21 pm

    I asked the BBC about this last year. I would say they tried to fob me off.

    Weather 21/10/16 at 11:12 AM
    ‘Ian Johnson’
    Message body
    Dear Ian

    Thanks for the email.

    I’ve spoken to some of the forecasters here and the reason is likely to be because of all the concrete – it is an example of an urban heat island. This is something that can happen with towns and cities which tend to be warmer than the surrounding countryside.

    You can find out more about that here –

    Best wishes

    BBC Weather

    —–Original Message—–
    From: Ian Johnson
    Sent: 20 October 2016 18:21
    To: Weather
    Subject: Contact Us feedback – Website

    Why is Heathrow airport so often the UK hotspot?

    • Hivemind permalink
      June 23, 2017 1:28 pm

      Actually, rather than fobbing you off, I would say they had pretty much admitted it. The only issue is the occasional time the measuring instruments get a bit of jet engine backwash, but I expect they don’t even admit that possibility to themselves.

    • HotScot permalink
      June 23, 2017 7:52 pm

      Gravesend near me in Dartford is frequently cited as the hottest evah in the UK at any given moment. I have no idea where the temperatures are taken there, probably in the middle lane of the A2/M/2.

  10. John F. Hultquist permalink
    June 23, 2017 1:26 pm

    All this proves is that the reported temperatures are only good for giving the temperature at the place and time reported. In this case, just what the pilots need.
    Any other use should be discouraged.
    A small airport near us reported 3.3 (6°F.) higher than at home yesterday afternoon. We live near trees and shade. Airport station is in a concrete circle where 2 runways come together.
    Any met office report should come with a disclaimer.

  11. MikeA permalink
    June 23, 2017 2:47 pm

    An important technical point, since we criticise the other side for making them, they don’t use tarmac at airports; it’s concrete. Tarmac is soft and its surface gets distorted – not good news for planes.

    Sums to the same selective site picking of course.

    • John F. Hultquist permalink
      June 24, 2017 12:08 am

      Good point.
      However, there are paved areas along side sometimes. A couple of years ago a large plane (U.S. southwest area, I think) got on to that. It was soft and the tires went in so deeply the plane had to be pulled out.
      A small town near us just replaced an intersection. The pavement from years ago (smallish trucks, then) could not hold up to large trucks mostly carrying apples.

    • It doesn't add up... permalink
      June 25, 2017 6:12 pm

      Not so. They use a hard grade of bitumen and lay it on thick. See the proposed construction profile for LHR third runway here:

  12. Sara Hall permalink
    June 23, 2017 3:43 pm

    Boulogne marina on Wednesday was absolutely roasting (at around 35deg), especially at low tide, but the day before in the English Channel it had been a most equable vest and shorts sort of day (until night fell of course and out came the thermals!) with just a gentle easterly breeze. But then, what does the temperature at sea matter when we all know that the most important and real temperatures must occur near where most people live nowadays?

  13. Chris, Leeds permalink
    June 23, 2017 5:32 pm

    From the HOURLY data on 21st June it looks like the Kew highest hourly temperature observation was at 5pm at 33.6c; Northolt also peaked at 5pm at 33.2C and Heathrow also at 5 pm at 33.9C….

  14. June 24, 2017 4:37 pm

    Reblogged this on Climate Collections.

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