The sun is getting weaker by the week. From about October 1 till March 31 the sun is too weak to make much, if any, Vitamin D in your body. People in Europe and upper North America used to survive by eating hog products all winter. Today's hogs have no Vitamin D because they are raised in warehouse factory farms. I have been taking 5,000 IU's / day of Vitamin D for 6-7 years as well as sunbathing 3 times a week.