The number of US homebuyers who signed purchase contracts shot up 6.1% in May, blowing away market expectations. A number of factors may be at work given that home sales are still below 2013’s levels. Economic weakness felt earlier this year was blamed on a harsh winter, so the rebound may be partially rooted in improving economic activity as buyers and sellers thaw out. But given the often local nature of real estate, weather can’t explain everything. Higher mortgage rates in the first quarter also held the market back. As rates decreased over the past few months, buyers became more aggressive.