Unable to pay the bills simply forecasting weather, three young people decide to sell weather itself, 50 pence the sunbeam, with predictable results. Using magic tokens, the Summer sisters Melissa and Patricia—plus little brother Arthur, whom they dub an honorary sister—actually predict the weather with perfect accuracy, but since the pounds just aren’t rolling in, the three turn to an overdue library book and dance up barrels full of rain clouds and sunny days to dispense. Disaster ensues, as first a vacation-ruining cloud gets in with the sunbeams, and then when Arthur accidentally snuffs out the sun. Supported by a cast of stock eccentrics and bemused parents, the sisters make a lively, contentious team, posing with disheveled grace in Kenyon’s small, frequent black-and- white ink drawings. (Fiction. 10-12)