Hundreds of refugees and migrants are believed to be in Calais and the surrounding area, a year after the Jungle camp was razed.
It is thought between 700 and 800 are gathered in France's northern port town, which continues to act as a magnet to those hoping to start a new life in the UK.
The number could be as high as 2,000 for northern France, Annie Gavrilescu, who works for charity Help Refugees, said.
She also said the charity was not allowed to give migrants any tents, for fears they would set up a new camp.
Footage from what used to be the old Jungle shows it now as barren land, and those desperately seeking shelter are forced to take cover in the thicket.
Ms Gavrilescu said: "While the French authorities are trying to prevent a camp, all we want to do is provide people with some form of shelter and protection. Unfortunately last winter, a few people in Greece and Serbia have died just of the cold and it is a distinct possibility that it could happen in northern France as well."
Speaking in Calais, Fawad from Afghanistan said: "We sleep in jungles and there is a lot of problem from police. They take our everything, tents, sleeping bags, clothes."
He added that the migrants were always on the run from police, fearing being beaten if caught.
Fawad, who only gave his first name, said: "We are afraid for winter. We will see what will happen because we don't have place to sleep and something to wear.
"And every day there is rain, it makes a lot of problem for us. That is why we are afraid from winter."
Hamad, who is also from Afghanistan, said that the blankets they have offer little protection from the rain, and the "freezing" nights.
On October 24 last year thousands of camp dwellers packed their bags on the first day of the Jungle exodus.
Calais has lived with migrants in its midst for years but the Jungle on the city's edge sprang up around a day centre opened in April 2015 by the state.
The population of migrants and refugees who fled war, poverty and persecution rapidly grew into the thousands.
Repeated bids to cross the Channel to Britain have been made by migrants, prompting an Anglo-French operation to bolster security around the ports, including the erection of razor-topped fences.
Last year French authorities cleared the camp in a bid to relocate people or send them to centres around the country where they could apply for asylum.