Charities have said that the heatwave in the UK is particularly dangerous for homeless people after the Met Office said continued exposure to the scorching heat could pose a potential risk to life and advised people to take extra precautions.

With temperatures in some parts of the country expected to hit 30C (86F) on Sunday, charities have called on the public to donate sunscreen and water to people sleeping on the streets.

“The summer can be just as dangerous for people sleeping rough as the winter months,” said Debra Ives, the director of operations for Evolve Housing + Support. “People sleeping on the streets are exceptionally vulnerable in the summer due to lack of access to shade, running water and sunscreen, which makes their life unbearable and can be a risk to life.

“We’re calling on the public to donate things like sun cream, water, and sun hats, to help those at risk this summer. People can either offer them directly, or donate them to a shelter or charity.”

Her calls were echoed by Crisis. “Rough sleeping is incredibly dangerous at any time of year, but as temperatures continue to soar, dehydration and heat exhaustion pose particular risks,” said Matthew Downie, the director of policy at Crisis.

“People living on the streets may spend nights on the move in order to stay safe, which means they often sleep during the daytime, so offering to help someone to find shade could save them from severe sunburn.

“Ultimately though, no one should be facing these dangers when we know that homelessness can be ended, so we’re also asking people to join our campaign to end homelessness for good, email their local MPs asking them to pledge their support to end homelessness and help us ensure that in the future, no one has to face these conditions again.”

In some parts of the country, homeless people have struggled to access free water, while many are unable to access public toilets, which are often inside shopping centres patrolled by security guards. Water fountains are often few and far between.

Outreach workers in Birmingham have given out bottles of water to the city’s homeless, some of whom had reportedly not drunk water for hours.

“They were so desperate, they were fighting over the bottles of water,” Tracey Patterson, the founder of Birmingham Homeless Support, told the BBC.

It is advised that people drink at least two litres of water a day during hot conditions.

“If I go into a shop or cafe and try and ask for a glass of water, they always say no,” Sarah, a homeless woman, told the BBC.

“If people think you’re homeless, they just won’t help you. If someone who didn’t look homeless went in and asked for water, they’d get it. It’s so frustrating.

“Security guards are always on the lookout for you. They think you’re scum. They’ll make sure you’re not in their place for too long, or just boot you out straight away so it’s hard to find shade for a long time.

“Even in parks and that there’s always someone to tell you to move on.”

Charities have said that to avoid being robbed or beaten up, rough sleepers often spend nights on the move and sleep during the day, making them more vulnerable to extreme sunburn.