When does summer time start???

[clarekpope]

What is the exact date of the start of summer??

[Clanad]

June 21, 12:46AM, Eastern Daylight Time in the U.S.,  this year... believe that should be 0746AM in London...

[kempie]

Almost... 00:46 EDT = 05:46 BST (for UK) or 04:46 UTC (GMT)

[kempie]

Just checked with HM Nautical Almanac Office and the summer solstice is at 07:46 BST as Clanad stated, it was the conversion to EDT which was incorrect - it should read 02:46

[Quizmonster]

Summer officially and scientifically begins at the solstice on 21st/22nd June and ends at the autumnal equinox on 21st/22nd September. However, it is obvious that standard phrases such as "flaming June" and "hotter than a June bride in a feather bed" have nothing whatever to do with springtime phenomena, which that official definition would largely mean!
As the second definition of �summer', The Oxford English Dictionary (OED) - the �bible' of words and their meanings - says: "in popular use, comprising in the northern hemisphere the period from mid-May to mid-August."
Traditionally, Midsummer's Day was June 24th and - in a temperate climate such as ours (UK) - the seasons are all about the same length...ie 13 weeks.  Accordingly, summer would, in most people's view, begin 6� weeks before June 24th, which is around May 10th and end around August 9th. That fits almost perfectly with what the OED says.
So, you can take your pick...the official definition or the one that common language and experience tells you is so.

[kempie]

"Hotter than a June bride... " - that's a new one to me.

Also do you not think it an enigma that the official start of summer is immediately followed by Wimbledon Fortnight - in most years a precursor for rain?

[landie]

Will someone please tell the Meteorological Office?

[Vectra123]

The Met Office will use the date 1st June for data recording purposes ie summer 1st june to 31st Aug, Autum = 1st sept to 30th Nov, Winter = 1st Dec to 28th/29th Feb and Spring 1st March to 31st May.

It is easier to work out monthly averages if done this way.