Paris is preparing for a street party of unprecedented scale on Sunday, as more than 2 million people are expected to gather for the Fête de la Musique amid a huge influx of music fans from the UK and warnings of record temperatures.

France’s annual free street music festival, which has been running for more than 40 years, has grown into the country’s largest cultural event. What was previously a nationwide showcase for local and amateur talent – from village choirs to classical ensembles and techno acts in the capital – has evolved into a vast international open-air celebration.

Last year, Paris welcomed a sudden and unexpected rush of music fans from the UK and other neighbouring countries after word spread on social media, creating an impromptu festival attended by about 2 million people.

Lamia El Aaraje, Paris’s deputy mayor, said “calls to all of Europe’s youth to come and party” in the city had transformed the event into “a kind of massive rave”.

She added: “Last year there was an impact on the public space, there were excesses, incidents, lots of sexual violence. We had a large clean-up issue afterwards so this year we wanted to mobilise ahead of time to secure the event.”

After reports of sexual violence last year – including some women and men who reported being pricked with syringes – authorities have adopted a zero-tolerance approach. Special cordoned-off safe spaces for women and disabled people will operate in key locations, including near city hall and Bastille, staffed by specialist support teams trained to deal with sexual violence complaints.

Paris city hall also warned international visitors about the dangers of canals and waterways. Last month, during celebrations after Paris Saint-Germain’s Champions League final victory over Arsenal, two people died in the Seine. One had a cardiac arrest after jumping in the river, while another was later found dead.

The city is also bracing for the practical consequences of hosting such vast crowds. Last year’s event generated so much litter that refuse teams needed two weeks to clear it. Thousands of additional bins and recycling points have been installed across Paris this weekend, while officials have urged visitors to use the city’s 600 round-the-clock public toilets rather than urinate in the street. About 1,400 water fountains will be available as Paris contends with heatwave conditions.

Pierre Rabadan, the city hall official responsible for tourism and nightlife, said: “The DNA of Fête de la Musique is kindness and lots of people. It’s a party that is responsible, joyous, happy and cosmopolitan. That’s all we want in Paris.”