Lowest Temperature Under Sunny Skies... In Summer!

[leicsnow]

I've been wondering, what would you say is the lowest possible temperature under crystal clear skies (or just virtually cloudless) during Summer in the UK, and under what conditions? Does anyone have any experience of strangely low temperatures under sunny skies? I'm talking maxima by the way.

[I remember Atlantic 252]

could only be off an Easterly I would have thought, 19C max ish, any other airstream NW or arctic, I would have though clear skies not possible due to convection

[Stargazer]

Good question. Thought I had only 12.2 on a sunny day on 12 June 2011, which seemed amazingly low until I discovered that I'd actually made a typing error and it was actually overcast and wet all day . I'd guess a sunny day with 17-18 deg C might be possible with a serious N/NNW flow, although down here in the SE that would be moderated somewhat and probably give us about 20.

[4wd]

With onshore breeze off the North Sea it can stay little more than the water temperature within a mile or two of the coast.

In june that could be about 10C or even less at the start of the month

[Harve]

Hardly the height of summer, but I remember a spell in early or mid March 2010 - near the equinox - having maxima of just 2-4c across the Midlands despite a moderately strong sun for the time of year and clear skies throughout. I believe minima were widely around -5c.

[leicsnow]

Hardly the height of summer, but I remember a spell in early or mid March 2010 - near the equinox - having maxima of just 2-4c across the Midlands despite a moderately strong sun for the time of year and clear skies throughout. I believe minima were widely around -5c.

I bet it felt more like 10 to most people!

[Thundery wintry showers]

I think in the Tyne and Wear area 12-13C is possible in June under clear blue skies, if accompanied by a cold NE wind off the North Sea. Quite often convection sprouts up inland in those setups while the coastal strip stays clear.

In inland areas the figures are probably higher. 14-16C is probably the limit across most parts of the country. You can add a degree or two to these values in July.

[conor123]

There's been numerous occasions in June where temperatures have peaked around 14/15c under sunny skies, temperatures can dip quite low here by night and rise substantially during the long summer days anyway, I remember during July 2006 temperatures falling to freezing in Shawbury.

[Eugene]

Hardly the height of summer, but I remember a spell in early or mid March 2010 - near the equinox - having maxima of just 2-4c across the Midlands

Yes the dewpoints were perishing in that cold spell, even in March especially the first half temps can be very cold under clear blue skies with a very cold surface flow.

In early June with a direct arctic northerly max temps of around 11C/12C are possible in the hillier rural parts of the midlands but you need a very cold northerly with no modification which is very hard in June, June still has pockets of arctic air to our north which by July are gone so early June to me is the coldest possible from a northerly in the summer maybe until the end of August.

[Terminal Moraine]

I had a look through my records and the lowest I can find since 1977 are ;

June 10th 1985 with a max' of 12.1c and 12.0 hrs sunshine

June 15th 1985 with a max' of 12.5c and 15.2 hrs sunshine

July 3rd 1990 with a max' of 15.1c and 13.8 hrs sunshine.

All of the above had a north westerly wind.

[cheeky_monkey]

could only be off an Easterly I would have thought, 19C max ish, any other airstream NW or arctic, I would have though clear skies not possible due to convection

Often easterlies bring hot sunny weather...1983 is good example of this and 1995...a straight artic northerly is the best bet 14/15c under sunny skies countrywide.

[Derp Patrol]

Down here we are sheltered from northerlies and north westerlies, and anything from the east is usually warm during summer. Under sunny skies it's pretty hard to drop below 20C even in a northerly. A few years ago in mid May we had sunny skies and a brisk northerly but temperatures were still hitting 22-23C

[leicsnow]

Thanks for the answers guys. To be honest, I'm rather surprised that maxima can be as low as 12c during a sunny June day.

[I remember Atlantic 252]

Thanks for the answers guys. To be honest, I'm rather surprised that maxima can be as low as 12c during a sunny June day.

I would have thought so, for our locations anyway, N and NW winds surely would not be totally clear skies from June to late Aug, Maybe NE winds would give clear skies and max temps of around 17C in late Aug, with low minimums

[Lettucing Gutted]

Under sunny skies it's pretty hard to drop below 20C even in a northerly.

I think last summer especially July especially in the very dry midlands was a great example of this point. Maximum temperates in July 2011 were often close to 20C give or take a degree or two but with almost consistently cold nights below 10C. Even more amazingly July 2011 often had northeasterly winds which usually mean persistently low cloud over the UK and yet it was often sunny over most of the UK which helped keep the maximums way higher than the minimums which were very surpressed due to clear skies, low dewpoints and cool uppers.

[Richard2901]

The coldest I can remember here for a day of full sunshine was 3rd June 2000 which was clear and sunny with 16 hours of sun but produced a max of only 13C. Also 14th June 2007 had 13.1 hours of sunshine but a max of only 12.1C.

For July, the coolest sunny day I can recall recently was probably 23rd July 2010 with 13.6 hours of sunshine and a max of 16.6C. However 16th July 1965 had a max of 15C with 14.4hours of sunshine.