I imagine that if I were to venture out to a metropolis which has the propensity for drop dead, low temperatures like say, Edinburgh, Scotland or London, UK, this time of the month; I would have the following items:
A tan, double-breasted, button-front trench coat from London Fog, there is something about a woman wearing a trench coat to me. It conveys confidence, readiness and a sense of adventure; like a female version of the predominant sleuths of our time - Sherlock Holmes, Colombo. Chic and smart!
Feminine-looking rain boots like this one from Hunter (Arolla). I would argue though that this might be big on the calf size for me (having chicken-thin legs) but alas, this is perhaps the only slim looking ones that I would ever be able to find among the plethora of rain boots all over the internet and retail stores. This one is useful as well as stylish.
A newsboy cap. For sure it will drizzle one time of the day in a place like London et al. and you'd want to be ready for such occasions. A cousin who lives there reminded me one time that I could possibly experience all seasons in one day in London. To that I will say, if it rains I'll have a cap and if it doesn't, I'll have an accessory!
Then of course, there are those items which you shouldn't leave home without anyway, like lip balms, hand sanitizer, small bottle lotion and so on, and so on... but that's common sense though, don 'it?