My hair looks oily when it's cold. It didn't come loose. ...

I believe your hair should not be very thick either. In summer, when the weather is dry, the hair will stand up after being exposed to the sun, which makes people look energetic and thick. In winter and cloudy days, the air is humid, and the hair absorbs the moisture in the air. Not only does the hair look oily, but people don't look mentally dirty. This is a matter of hair quality. Choose a shampoo suitable for your hair, wash your hair frequently, usually once every 1-2 days, and don't scratch it often, because there are many hand injuries in winter, and once you scratch your hair, you will get oily. Keep your face clean.