Save (something) for a rainy day. This idiom often used to describe saving money or something of value to provide contingency for when times are tough. Though it is unclear how this expression began, it is indisputable that the "rainy day" is symbolic of financial and emotional gloom.
It is difficult to disassociate rain with gloom, especially since this affiliation can be traced to the 16th century. But what if saving for a rainy day were instead associated with the luxuries we find hard to enjoy during our over-charged lives: an opportunity to lose ourselves in a book, watching a movie while laying close with our loved ones, lingering over a home cooked meal, or even braving the weather, snuggling under one umbrella with our partners and exploring our neighborhood in the new light and textures the rain brings.