THOSE who live on America’s coasts know to prepare for wrathful hurricanes in late summer—nailing plywood to their windows as the storm approaches. America’s property insurers and reinsurers are ready, too, using sophisticated models to track storms and estimate potential losses. But wind is not the only danger from hurricanes. Ask Houstonians who saw their homes inundated by Hurricane Harvey’s 52 inches (132cm) of rain in the six days to August 30th. Or those in tthe path of Hurricane Irma, which, as The Economist went to press, was wreaking havoc across the Caribbean. But whereas wind damage is covered under most standard insurance policies in America, flood insurance is a government-run add-on that far from all homeowners buy. As a result, of over $30bn in property losses in Texas, only 40% may be insured.