As 2010 is a Jacobean year, it is either the best or worst time for you to do the Camino de Santiago. Read more about Jacobean Years.
The terrain varies greatly on the Camino de Santiago. The mountain passes are extremely dangerous in winter. That isn't to say it isn't possible to do the walk in winter, but heed the advice of other travelers and the hostel staff before you set off each morning. Follow the weather forecast. Be prepared to take a safer route and even abandon your trip if necessary.
Summer travel on the Camino de Santiago is very different from doing it in winter. Lots of people filling up the hostels means you will need to set off very early in the morning to get a good hostel. Though weather conditions are unlikely to prohibit you from finishing the Camino de Santiago, the host conditions might make the journey unpleasant or even unbearable. Drink lots of water if traveling in summer.
Read more about what to expect in each month on the Camino de Santiago: Camino de Santiago - Month by Month