[FuzzyUK (OP)]

Yesterday was the hottest day in the UK with temperatures reaching 38.1C (100.6F) in Cambridge.

However, the Digital Technology Group that runs the weather station at the Cavendish Labs in the City only recorded a maximum temperature of 36.1C.
https://www.cl.cam.ac.uk/research/dtg/weather/daily-text.cgi?2019-07-25 

How come the 2 degree difference in temperature measurement? What do we know about these two different weather stations and where is the one located that the Met Office rely on?

[evan_au]

Today I arrived in Helsinki, Finland.
The weather forecast is for 33C on Sunday - the locals think that this is definitely too hot for Summer!

It's possibly that same puddle of hot air drifting westwards eastwards from Cambridge Boris Johnston...

A cool change predicted for Monday.

Edit (thanks to Alan Calverd).... Everything seems upside-down in the Northern hemisphere....

[FuzzyUK (OP)]

It's possibly that same puddle of hot air drifting westwards from Cambridge.

No, the winds were bringing the heat from Africa.
What I'm curious to know is whether local traffic jams can affect weather station readings.

[alancalverd]

Oddly, the Met Office doesn't seem to record temperature at Cambridge airport, where it actually matters! However at 1400 - 1500 yesterday the Met Office station out of town at Histon recorded 41C whilst the temperature in town at Chesterton was "only" 38C.

Whilst we generally regard cities as heat islands, it is noticeable that Mediterranean cities have tallish buildings with narrow streets, so the bit where people live and do business is mostly in shadow, with sunlight reflected from roofs and the considerable thermal inertia of brick and stone evens out the day and night temperatures. So it is entirely possible that a village green  surrounded by low buildings gets a lot hotter than a city street during the day.

The hottest places I can find on yesterday's map were villages at Mereworth (Kent) 44C and Saxilby (Lincolnshire) 43C, again a few degrees hotter than the nearest town.   

If Helsinki really is west of Cambridge, that would explain why I sometimes get lost, but my copilot puts it down to having the map upside down.

You can certainly brew up in a traffic jam but official weather stations tend not to be at roadsides. Slow traffic in town  will heat the air but a good solid motorway tailback probably won't have much effect until the ambient temperature exceeds 25C, at which point everyone will start his engine to run the aircon!

[FuzzyUK (OP)]

Here's another oddity. After two days the Beeb say the temperature could have been 38.7 deg C (not 38.1) but they are waiting for the Met Office to confirm that.  For crying out loud, how long does it take to verify?  If they can't get it right in the first place who are we to believe about the reliablity of so called global warming stats?

[Bored chemist]

It is precisely because the Met Office takes the time and trouble to confirm things that most people may consider "obvious", that we can trust them regarding things like global warming.