Paris pools will host night swimming, large parks will stay open all hours and special “cool rooms” will be set up in town hall buildings as French authorities fear for residents’ health during the anticipated European heatwave.

The French capital still carries the trauma of the 2003 heatwave, which caused many thousands of deaths in France and so many deaths in the Paris area that morgues ran out of space.

Elderly people and those living alone without contact with neighbours are a particular concern as the city increases emergency planning. There will be special phonelines, and “cool rooms” will be available between 2pm and 6pm across the capital.

The Paris mayor, Anne Hidalgo, said on Sunday that as many as eight major swimming pools would stay open after 10pm and swimming would be allowed in the canal basin at La Villette. She also said three temporary outdoor pools would be set up for in highly populated, lower-income areas of the city, which would be free to use.

Paris has relatively little green space and has been working for years on how to “green up” and introduce more plants in order to counter the heat held by stone and concrete. Hidalgo told the Journal du Dimanche that 13 large parks would stay open all night during the anticipated heatwave because the temperature there would be one or two degrees lower than in the rest of the city. She said five more parks would be added if the heatwave continued.

The city’s growing homeless population, which includes high numbers of migrants who sleep rough in groups of tents under bridges or by roads, is also a particular concern. Hidalgo said 5,000 reusable flasks of water would be distributed to people living on the street, and more than 1,000 drinking fountains added across the city. Aid workers would increase their rounds of the city to check on rough sleepers, she said.

The homeless help centre at La Chapelle, an area with large numbers of undocumented migrants and refugees sleeping rough, “would stay open seven days a week, with a capacity for 400 showers a day”, she said. Campaigners have long complained that not enough year-round support is available for the city’s homeless.

Hospital emergency rooms in Paris are braced for an increase of patients just as many have led strike action over insufficient resources.