On that note, I'm therefore wondering whether or not, the value of 14.0% (temperature = 14.3°C, dew point = -2.9°C) for the relative humidity which was recorded last night at around this time, at the botanic gardens in Edinburgh could actually be the all-time record for the lowest ever recorded relative humidity in this part of the world.

Even if this doesn't actually beat that all-time record, it wouldn't surprise me if we were close to it there with that one. Just now though, the relative humidity has gone back up to around the 50% mark at all three of my local stations but even that is very low for this part of the world.

What is the altitude, distance from the sea, distance from the city centre and aspect of the botanic gardens?

The latitude and longitude of each of my three stations is always shown on the signature at the bottom of my posts and from there, you will see that the botanic gardens in Edinburgh is 26m above mean sea level which makes that the lowest of my three local stations.

You could punch the given latitude and longitude for that into something like Google Maps which will then take you right there. That will then let you know exactly where it is in comparison to Edinburgh city centre, although I would say it is about a mile or so away from the city centre and it is also the closest of my three local stations, to the east coast which is probably about a couple of miles or so to the north.

Alternatively, you can find out more information about its location (including details on how to actually get there) from here. Furthermore, you can also get the details from here about the weather station which is there, which is the closest major station (discounting all of those much smaller local stations which appear on wunderground) to where I live, and which I use as one of my three local stations).

Very dry air around today too. RH down to just 31% here.

It also makes me very dubious as to whether any showers will develop this afternoon, unless it rises very sharply later.

Lowest Humidity 22% rh  at 09:46    20-05-2018.

I have noticed a lot of variation on Wunderground station, caused by different set ups.

There's probably a lot of 'real' local variation too

And a lot of dodgy/dirty sensors.

https://www.metoffice.gov.uk/public/weather/observation/gcnjj7h5w 

13% at Filton, for example: air temperature 29.4, dew point -1. (That's more like Vegas- albeit in the spring - than Bristol!)

Saturday's 24% was the lowest here since I started recording humidity in 2008.

For this to happen in summer with an air temperature of 25c and a dewpoint of just 2c is the stuff of deserts. 

How come they're so low? Been as high as 15C along the coast this way. 

A rare culmination of a stable WNW'ly airmass in high pressure and a light breeze that had the benefit of a 250 mile land track having descended and dried across the Welsh mountains, the Maverns, the Cotswolds and then the Downs. 

Thanks for the explanation 😊

We've had southeasterlies today, and southerly v southeast yesterday.

Currently  28% here in Dartford.

31% rh. In PSJ.