After such an abysmal summer it hardly seemed that the weather could get much worse, but the weekend was yet another great washout. The finger of blame points, again, at the jet stream, the high-level winds that whip around the globe at great speed and help to drag depressions across the Atlantic to Britain.

The jet stream has been tracking unusually far south these past several weeks, tearing over Britain with barrages of wind and rain. But this weekend it also developed a large kink in its flow that behaved like an exhaust pipe, sucking out air from a depression below and turning it into a beefy storm.

There is more trouble on the way later this week, as the jet stream spins off an eddy of bad weather that could meander around northwest Europe, possibly hitting Britain. Another explosive element is the remains of Tropical Storm Hanna, which will dump its cargo of hot air over the Atlantic and stir more stormy weather our way.

The reason that the jet stream has aimed towards Britain is possibly because the tropical waters of the Pacific turned unusually cool, a phenomenon known as La Niña. This knocked the jet stream off course, but now that La Niña has given its last gasp, conditions over Britain had been expected to improve this month.

The Met Office’s seasonal forecast for autumn points to a heart-warming return to something drier and warmer than normal. When those halcyon days arrive remains to be seen – “Indian summers” often fall in late October, which would coincide with school half term – but one is needed desperately. With the ground soaking wet and evaporation declining as the days grow shorter, there is the growing threat of severe flooding unless the rains stop.

Certainly, if this month’s rainfall carries on this hard it could break the record rainfall of September 1918, the wettest in 242 years of records, when it rained every day over much of Britain. It was also one of the coldest and windiest Septembers of the century, and left the harvest in ruins and the Western battlefront of the First World War deep in thick mud.

However, despite the downpours this summer, it was nothing like as bad as last summer. True, August was wet, but England and Wales had 119mm (4.7in), far less than the dreadful August of 2004, when 156mm rain fell, and piffling compared the record 193mm in August 1912, when Norfolk was marooned in a sea of floodwater. And this summer was not particularly cold – amazingly, it was the 96th-warmest summer across central England in records going back 350 years.

One feature does stand out. August was the gloomiest since sunshine records were first collated in 1929. Day after day the Sun was blotted out by thick, grey blankets of stratocumulus or billowing cumulus clouds. Only 105 hours of sunshine broke through, two thirds of normal. That lack of sunshine has led to a rise in seasonally affective disorder, a depression caused by lack of daylight and more usual in winter. Many people also lacked enough sunshine to make sufficient vitamin D for the winter.

“It is a concern that we’re not getting enough vitamin D. That puts people more at risk of osteoporosis, diabetes, certain cancers and many other diseases,” said Inez Schoenmakers, from Human Nutrition Research, in Cambridge. Those deficiencies can be made up with foods rich in vitamin D, such as oily fish and egg yolks, or artificial supplements.