The moon is bloated but nights are now dark. Some warmth remains and in fortunate years, one evening will be chosen to spread outdoor trestle-tables with paper tablecloths, get out the paper lanterns and plot the crayfish party! Here, hearty indulgence in hard liquor is actually encouraged.

The kräftor (freshwater crustaceans, crayfish, mudbug, crawdad) are boiled, steeped in dill and brine, then sucked and devoured. Flimsy paper hats are put on and ditties are sung. The short, pithy drinking songs, unique to Sweden and Swedish-speaking Finland, are the nation’s living poetry: every year new songs crop up to be remembered and repeated at next year’s parties. The song canon tends to the farcical. And what a joy it is to witness one’s normally reserved acquaintances, now giggling and tipsy, shouting risqué doggerel.

Drinking habits at crayfish parties mirror the nation’s: a few people get plastered but most drink at a tacitly agreed pace. Aficionados take as much care as winemakers in flavouring grain or potato vodka with herbs and spices such as horseradish or roasted fennel seeds. Or forest fruits like rosehip, lingonberries and blueberries.

The third Thursday in August is the unofficial opening of the fermented herring season. This is Baltic herring soaked in lactic acid and packed in cans that literally bulge with odorous gases (hydrogen sulfide, butyric acid, etc.). Some airlines won’t let you pack the tins because of the pressurisation issue but the tins don’t actually explode.

Because the Baltic Sea is brackish, not saline, northern Sweden used to lack easy access to salt. Innovation was needed to preserve food. Pickling, curing and drying are still widely used. The herring was sealed in barrels left outdoors for the spring sun to heat. Statistically, heat would spark the process in mid-April. Eight weeks later, trucks would load the cans and speed out from the salting-house gates promptly by the third Thursday in August. State control over the quality of foodstuffs turned into an excuse for a big party.

Thin filets of innocent-seeming but pungent fish are spread on prime hard bread. Chopped raw onion and boiled almond potato as company. Purists drink milk.

On 10 August 1628, the pride of the Swedish navy, the warship Vasa, sank in Stockholm’s harbour. She was on her maiden voyage, overloaded with cannon and 500 sculptures, including 60 of lions. King Gustavus Adolphus had ordered extra cannon, making the ship unstable. At the seaworthiness trial, crewmen ran from one side of the ship to the other, but the test was quickly called off because the ship was pitching so violently. Who would tell the King? Apparently no one did, because the ship went down only a few hundred metres from its launching place. Shock or embarrassment erased the memory of the shipwreck site until a lone researcher found it 333 years later. The world’s only surviving 17th-century ship, now battling only wood-eating sulphuric acid build-up, rests inside a world-class museum in Stockholm harbour with 25 million visitors at last count.

At the end of the month or the beginning of September, the annual measurement is made of Sweden’s highest mountain, Kebnekaise. Because the peak of the currently 2,111 metre-high mountain is glacier, global warming is whittling it down — it is currently 20 metres lower than when first measured. Kebnekaise is the jewel of Sarek National Park, one of 28 protected parks. Sweden was the first country in Europe to have them. And August is prime time on the hiking trails. But watch out, by the end of the month thunder and gales are ready to pounce.

By the last week of the month, schools are again filled with the eager, the reluctant and all their friends. A new academic year has begun.

The Year in Sweden by Kim Loughran is on sale now at the AdLibris online bookstore.