If a fire engine red trench coat is not your style (I realize it's not everyone's cup of tea), another way you could introduce color into your ensemble is a bold lip color. A coral or fuchsia lipstick can illuminate the face and ever so slightly give you more confidence to face the gloomy day ahead, without forcing you to commit to wearing a technicolor raincoat. You never know, it could end up being your signature look regardless of whether the sun is shining or the sky is covered with clouds (I'm looking at you MC).
Top: Gap. Skirt: Zara. Belt: Gap. Trench Coat: Juicy Couture. Shoes: Fendi. Umbrella: Leighton. Jewelry: David Yurman, Hermes, Topshop, Target, Gift from Italy. Purse: Courrèges Paris.