Within the confines of his tent, Henry could still see his breath as he woke up.
As the knights traveled north for the battle, the weather got progressively worse. The north was away from the sea and at a much higher elevation. Colder weather settled in quickly the further they traveled.
They were in the midst of mountains, moving at such a slow pace because of the rocky terrain and incline. They had to get off of their horses so their horses wouldn't get harmed by the uncertain footing.
At first, Henry didn't know how to cope with being cold all the time. The first few mornings he spent traveling, he thought his hands and feet were going to fall off when he woke up in the morning - only to feel relief when he started moving around.
Eventually, he was forced to adjust. The other knights didn't seem to find any issue adjusting to the cold.