Whilst pine trees are evergreen and keep their leaves all year round, they do actually replace the needles over the course of the year. It is quite natural for the tree to shed some needles at this time of year and, appart from dead needles at the base of the tree, it should not be noticable.
If, however, all the needles are going brown and falling off in great numbers then the tree has a problem, possibly lack of water. If you are still haveing very dry and windy weather then I would try giving it some water.