The House of Defence, Volume I by E.F. Benson

It was mid-June, but no Londoner of any intelligence could possibly have guessed it, because, instead of the temperature being absolutely Arctic, it was extremely warm -- a condition of things which in England we are not accustomed to associate with the midsummer months. Middlesex, we must suppose, had somehow come into conjunction with the Dog-star, who had bent his beneficent rays onto the county, and given birth to a whole week-long litter of delicious dog-days. It was really hot; there was really a sun, a big, blazing, golden sun, instead of the lemon-coloured plate which in general shines so very feebly and remotely through the fog and dark mists of Thames-side, and this was not only delightful in itself, but it actually made the shade a delightful thing to get into.

The tops of omnibuses were thick with folk, and the Londoner of even the parks and palaces left the black silk tube, with which he is accustomed to roast and destroy his few remaining hairs, at home, and wore a straw hat instead, even when he went out, as he usually did, to lunch -- and didn't care. Indeed, there was no reason why he should, since only the obviously insane wore top-hats in such weather, and insanity was surely a more serious defect to have on the head than straw. A thin blue haze hung over distances. Piccadilly, a hundred yards away, had a bloom upon it like the dust on a ripe plum, and horses (those intelligent animals) had followed the lead of their masters, and wore straw hats too, with rims coquettishly raised at the sides to allow plenty of ear-play.