They say midsummer brings out the madness in all of us, so don't be surprised if in Alicante in June you see apparently normal people leaping over bonfires on the beach at the dead of night and running into the sea.

The longest day, which is officially the summer solstice, is June 21, however, the midsummer celebrations take place throughout most of Europe, and particularly in Spain, two days later, coinciding with St John's (San Juan) day on June 23.

Alicante's San Juan celebrations are perhaps some of the largest in this region, and you could be forgiven, on taking a stroll through its streets this month, for thinking the Fallas (fiesta) had made an early comeback.

Immense papier mâché statues – known as hogueras or fogueres, which means bonfires - usually caricatures of politicians or celebrities, or satirical illustrations of newsworthy events, adorn the streets from June 20 onwards. Like the Fallas, they are set fire to at the end of the festival, but not until a day after the rest of the world celebrates San Juan – in Alicante, it takes place on June 24 at midnight.

The electrifying, colourful end to the fiesta starts with a huge firework display in the Benacantil district, near the city's famous Santa Bárbara castle, and is said to be so enormous that it can be seen from the coast along most of the Costa Blanca. Next, the monuments go up in flames, one by one, ending with the winner.

Overall, Alicante's version of San Juan has been granted the status of a Festival of International Tourist Interest, meaning it attracts holidaymaking crowds from all over the globe, much like the Semana Santa celebrations in Sevilla.

In the same manner as the Fallas fiesta, the San Juan celebration has its own fiesta queen, known as the Bellea del Foc ('beauty of the fire'). Being nominated for this coveted status is an expensive hobby, but a huge prestige for residents of the city.

The festival was originally a celebration of the longest day – allowing more time in the fields to bring in the harvest – and the shortest night, meaning less time for curses and evil to attack. But the council, fed up with the noise and mess, published a sign forbidding anyone from letting off fireworks or setting up bonfires in the street, on pain of a huge fine.

In 1881, they forgot to publish the prohibition order, so the townspeople took advantage and built satirical statues, held dances in the street and organised open-air concerts and firework displays. Yet it wasn't until 1928 that the San Juan fiesta became officially-recognised and the ban was lifted.

Elsewhere in the region, San Juan is indeed celebrated, although it is a much more low-key affair. The fiesta is known as Las Hogueras de San Juan – literally, St John's Bonfires – since these are the protagonists of the event. Traditionally, it involved burning old furniture and other household junk in the streets, but has graduated into a series of fires being lit – mostly on the beach, in coastal towns – that burn long into the night.

Legend has it that you should leap over the bonfires and make a wish. If the festival takes place on the beach, you should then run into the sea and leap over the waves. It is also said that you should write down your heart's desires on a piece of paper and throw it into the flames. Many locals swear by it, with some claiming that their dreams, after being reduced to ashes on San Juan night, always come true.

Even if you're not in the city of Alicante on June 23 this year, but you are in the region, head to your nearest beach, armed with your wish-list, and witness some authentic midsummer madness.