Jonathan has braces on his teeth and was wearing his school uniform
A father has made an emotional appeal for his missing son to come home or anyone who has him to "release him".
Jonathan Marques, 15, of Whitley, Berkshire, left home to go to school in Southcote on Tuesday but he never arrived and has not been seen since.
His father Menino Marques said he needed to know his son was safe and his mother wanted to hear his voice again.
Police are growing increasingly concerned at the possibility Jonathan is outside in bitterly cold conditions.
Mr Marques said: "First of all I beg to who has kept my son to release him from that place.
"His sisters and brothers want to see him, his mother wants to hear his voice say 'mama'.
"Just ring for us if you are well.
"If anyone has kept him just release him from the house."
Jonathan has braces on his teeth and was wearing his school uniform, which includes a maroon sweatshirt and dark trousers.
Jonathan's parents made an emotional appeal for information
He was also wearing a grey coloured hooded top and carrying a dark rucksack.
Chief Superintendant Richard Bennett, of Thames Valley Police, said: "We've had a couple of calls but none of them have proved to be positive lines of inquiries.
"If he is trying to stay out in the open in these bitter conditions that is obviously a serious concern for his welfare.
"It is possible he may be staying with a friend and we are pursuing lines of inquiries with the school.
"His family are extremely worried for his welfare as are we."