When temperatures drop below 18C, snowflake patterns will appear on this thermochromatic Jack Frost scarf from Diana Eng. But that's like using a bandage that tells you you're bleeding, or a hat that points out your hair's a mess.
If you're planning to spend the summer in the northern hemisphere this year where, as nature would have it, it's actually winter right now, you might have need of this quirky piece of clothing. Let's ignore for now that if you're already wearing it, chances are you already know it's cold.
Of course the scarf is supposed to be considered more of a whimsical fashion accessory than a $US60 cotton thermometer. But a scarf that actually had the ability to tell you if it was needed, or an umbrella that predicted rain, would certainly be embraced by geeky fashionistas. [Diana Eng via CNET]