Someone pointed out in one of the London free papers that we have had bad summers ever since he became prime minister. I don't think that the jet stream has been drawn south by his doleful visage. However, the wet weather does not nothing to create a 'feel good' factor.
It may seem to be a trivial matter that the Met Office got its 'barbecue summer' forecast badly wrong even if they are now claiming that they only forecast it as 65 per cent likely (but then why put the 'barbecue summer' heading on the press release?) Some families, also influenced by the state of the pound against the euro, may have planned a 'staycation' as two of my children did. Now there is a last minute surge of bookings for Southern Europe.
I had better weather in Chile where it was winter than I have had in Britain. Although it was chilly (excuse the pun) at night it was warm enough to eat outside at lunchtime. And there was no rain.
I do recall some political science literature on the effect of the weather on elections, mainly in terms of whether there was any effect on turnout. I do remember trying to get voters out in a Glasgow ward in 1969 where there was a tight three-way contest. It started to pour with rain in the evening, but fortunately a ride in a car was enough of a novelty to entice some voters to the polling station.