Late night winter wear shopping in Helsinki?

Hello, My husband and I will be landing in Helsinki at 8pm. Our tour starts the next day early morning so we won't have time to shop for winter wear like a Down Parka. We are from India(very warm country in many parts) and we could not find down parka or winter wear for surviving -20°C. 😅 The only time we will have in Helsinki is at night, will there be any shops open so we can quickly buy winter wear and not ruin our trip because of cold? Any other suggestions are also welcome.