I would say bring her in as soon as you can catch her. My Mama cat was the same way before I brought her inside. She would rub and meow and she loved Casey. However, she would not let me pick her up. After she had the 3 kittens and I brought the kittens inside I tried for a couple days to catch Mama. Finally I got her and held on tight until I got her inside. Once she sees you love and care for her she will come around. Mama wasn't a lap cat for a long time and also would only let me pet her if she was on my bed. Now she gets on my lap, purrrs (which she did not do in the beginning either) and lets me pick her up. It is a slow process but once they come around it is so rewarding.

Good luck. I hope you can get her inside where it is safe and warm.