I'd like to point out that Next and other retailers still can make money in good weather as well as bad. They may gave sold off a lot of Summer stock in their last sale but it's unlikely that their customers will have been shopping for swimwear instead of winter coats - the weather hasn't been that good!
Retailers have analysts galore to loom at all sorts of trends from weather to the harvests of the produce they sell, so it's unlikely that the recent good weather will have been totally unpredicted.
The stock that all retailers, especially the local entrepreneurial type I envisage reading this blog, have sat in stockrooms or storage will get its turn when the weather does eventually turns cold (it will, it's the UK.) It's just ensuring that you are ready to trade 100% when this happens.
Stsrt to make sure that you can access this stock at short notice, that it's listed on your main and mobile websites and that it's available now via Click &Collect if not already in store. It's by having these conrngemcies in pomace, and by having great conversations with your customers that you will be in the optim position to reap the rewards when the template is right.
If your retail unit is affected by the weather via what stock you carry, then stay tuned to the medium and long range forecasts, as they can and will give you an indicator of the general trading conditions you are likely to face, and give you pointers on how to react.