Collapsible Umbrella
You carry a collapsible umbrella if the weather is too good for a coat, but perhaps it . . . might rain later?
Of course these things are utter garbage. The moment it starts raining in earnest the umbrella turns inside out and the metal bends. It then ends up in the nearest public waste bin, still flapping in the wind.
There is a collapsible umbrella for every walk of life. Some mothers carry collapsible umbrellas as part of their handbag kit. Some kits carry them in schoolbags. Some super trendy businessmen carry them in their inner suit pocket, since wearing a coat makes you look less uber business chic but wearing a wet suit is even worse!