This is one of the most commonly recited superstitions of our age and the evidence suggests that it is of comparatively recent origin, as umbrellas weren’t widely used until the nineteenth century. Fans of speculation and conjecture might appreciate the following unverified offer of explanation: the earliest umbrellas were used as sunshades rather than to keep the rain off and in ancient Egypt, where such parasols were used for this purpose, ceiling-less temples were constructed for the worship of the sun gods. Some sources have it that raising an umbrella inside such a temple was a direct affront to the gods and a rejection of the sun’s blessing, for which there was a hefty price to pay.
As there is no documentary evidence of this belief in the numerous collections of superstitions made in the years between the fall of the ancient civilizations and the nineteenth century, it seems that an alternative explanation is more likely, if less beguiling. One of these is the possibility that the umbrella, along with other upturned items in the home including lucky horseshoes hung in the open-end-up position (see Horseshoes), could be used as resting places for mischievous fairies and pixies. Some word-of-mouth reports of this superstition include stories of goblins living in folded umbrellas who might be released into the home if you opened one indoors, and these kinds of superstition were commonly handed down through the generations with small modifications to allow them to fit the living arrangements of the day.
The exact nature of the misfortune due to rain down on you if you do open an umbrella inside varies from era to era and place to place. These days it’s mostly just considered ‘bad luck’, but in the late 1800s opening one and holding it directly above your head was said to be a sign of a forthcoming death. A version of the superstition that appeared in a compendium of American folklore published two decades ago suggests that by opening an umbrella beneath a roof, the guilty party forfeits the protection that the house has to offer. Most superstitious homeowners took care to ensure that their house was protected from the influence of evil spirits through the placement of a talisman or ‘lucky’ charm at the entrance, but opening an umbrella within it created a kind of independent realm, existing under its own jurisdiction and lacking the blessings required to keep you safe within it.