Also, when it rains in the morning when you go to work, but is sunny and not so cold when you head back home (or the other way around). Obviously, you _could_

Also, when it rains in the morning when you go to work, but is sunny and not so cold when you head back home (or the other way around). Obviously, you _could_ carry two jackets in that case, but if you live in London (like me) there's no way to know for sure which you'll need before you leave the house.