The average weather conditions for Faro:
Weatheronline reports:
The average daily maximum temperature for Albufeira is between 15°C and 18°C. At night it cools down to temperatures between 8°C and 13°C. On average there are 3 days with precipitation. The daily sunshine duration is about 5 hours. On average there is a gentle breeze of 3 Bft (Beaufort Force). This analysis is based on data from the past 10 years.
Have a look at this site:
http://albufeirawebsite.com
It can be a bit parky but if you get a warm day it can be nice.
Many places do close in early December but open again for Xmas.