Dr Irfan Noor is keeping a diary for the BBC News website as he travels into Pakistan's North West Frontier Province as part of a medical relief team.
From remote Odhi district, he warns that the cold could claim more lives unless tents are provided.
Odhi, Thursday 13 October, 1630 local time (1130 GMT)
All the medical buildings here have been damaged.
There are thousands of homeless people and an acute demand for shelter. Many of the houses are destroyed and Odhi is situated at a very high altitude, so the situation is critical. It's just freezing here.
We saw children outside without any shelter. We need at least 20,000 tents here alone.
They were in extreme psychological trauma. They were desperate because they have spent four or five days in the open.
Everyone is going to Balakot but that is a dead valley now. What about the rest? We know that there are still people in villages beyond, but everyone goes to this town of ghosts.
All the agencies are now co-ordinated and united - but that doesn't mean we have what we need. We are out in the field and we see with our own eyes that things are beyond the government and the army now.
We need international aid from all over the world.
There were two major aftershocks today. I saw the mountain and it looked as if it were about to split into two. An enormous rock was precariously suspended above us.
It could have killed us.
I've seen doctors in tears. They are on the frontline and they are working with people who are dying, people without shelter, sanitation, and they cannot cope with the trauma.
But I have also seen truck upon truck of aid from ordinary Pakistani people. My UN colleagues have told me they have never seen anything like this. It makes me feel proud.
It is the one positive thing amidst all this misery.
Balakot, Thursday 13 October, 1630 local time (1130 GMT)
There is not a single building standing in Balakot.
There is an extremely foul smell because the city is full of dead bodies.
We are focusing our efforts on surveys and logistics. The population of the city was about 24,000. It looks as if 70% of this population has been wiped out. Our data will help the government revise its figures.
The death toll will inevitably rise.
There are a few people still alive and a Chinese agency has set up a first aid camp. Another team from UAE has taken up the job of disposing of dead bodies.
There is talk of mobilising the population that is left and spraying the rest of the area, because of contamination fears.
Tomorrow I'm going to Odhi, a place nobody has yet reached.
There are airlift helicopters dropping food, tents and medication throughout the Mansehra district: the population is very scattered over there.
I have just felt a significant aftershock. Those people who are still in remote areas must be terrified.
Their first need is shelter. Temperatures are extremely low. People now have food and medicine, but shelter is what they desperately need.
The onset of the cold has changed all our priorities.
I can see that relief supplies are coming in, but tents please, more tents.
Mansehra, Wednesday 12 October, 1300 local time (0800 GMT)
There's a place called Jabouri, north of here. The road has been blocked by a landslide and beyond that there are many, many villages.
Let me give their names because most people won't have heard these names before: Manabocha, Jhacha, Pandur, Batangi.
People have come from these small mountain villages carrying the injured on their shoulders, walking for hours. We have heard horrific stories. The situation there is drastic.
Each village has about 250 houses, all of them are destroyed and in each home, people have died.
The government is not calculating fatalities properly. We have a survey team going to Balakot and they will establish numbers.
I have a feeling that in Balakot alone the death toll might be 15,000 or 20,000. But that is not official, these are just guesses - our team will collect data and supply it to the appropriate sources.
There are teams from all over the world and somebody has to co-ordinate them. We are going to lead them to the areas facing the direst need.
I have seen hundreds of patients here. There has been an outbreak of chest infections, respiratory tract problems here.
Supplies have only just reached here. Doctors are performing surgeries but without sterilisation equipment, surgical tools, without proper sanitation even.
Patients need to be taken to Peshawar. It has three huge hospitals waiting for patients - but they lie empty.
I'm very tired, but every hour is important.
I can see the distant mountains from here - they are covered in snow. Last night the temperature fell so low and I could only think of those people homeless outside, those villagers still trapped.
Mansehra, Tuesday 11 October, 1600 local time (1100 GMT)
I reached Mansehra with a UN team just a few minutes ago. The roads are crowded and it was a long, arduous journey from Abbottabad.
I am standing inside the main hospital. These newly-constructed buildings were totally damaged before anyone got a chance to use them.
The patients are outside under tents. I can see some being carried in by stretcher.
One thing is clear. Medical supplies have not reached Mansehra.
People are in a terrible condition but there is not much that doctors can do. We don't really have the right surgical equipment.
We have kidney specialists, we have some dialysis units but there is no electricity and no water so how can we install them?
There is no logistical organisation. We have no idea how many supplies are really needed, how many patients there are, how many there could be, even how many doctors are in the area.
We see Swiss and Chinese relief teams but even they are in chaos.
I have plans to head to even more remote northern areas.
I've spoken to a colleague who says that the town of Batgram has been levelled and there are serious casualties - an incredibly high death toll.
There are many dead bodies, but more importantly there are people still alive, still trapped.
One final plea is that we need helicopters urgently.
Peshawar, Monday 10 October, 1500 local time (1000 GMT)
When the earthquake struck, I was in the Ayub medical complex hospital at Abbottabad.
Much of the hospital was structurally damaged during the earthquake. Ceilings caved in, the emergency room had to be closed down.
Resting in hospital grounds in Abbottabad
After a few moments, huge panic set in. People started to pour into the hospital.
There were people dying, being separated from families - a huge mob filled with pain. There were aftershocks, and all people could do was lie down. The casualties were enormous.
In this city alone, buildings, plazas, shopping centres just fell down.
This is a city, what is it like in the villages?
And it took well over a day for any relief to start coming. They were busy in Islamabad not thinking of the thousands of people still trapped in these rural areas.
In the evening it rained and hailed as a huge storm arrived. It was unimaginable. People were out in the cold, terrified, grieving.
There is no shelter, lots of women and children are braving the extreme weather without food and water, becoming infected by pneumonia.
The psychological trauma is difficult to cope with. We try to reassure them but what can we do when these people have nothing?
They have only their injuries. Their houses have been demolished, they have no money, no place to go.
This is a rugged and remote region. Abbottabad is a city in a valley.
From Tuesday I will venture out into the mountainous areas, where I hope to make use of my skills.