Friday marked the hottest day in August for 17 years. The weather isn't the only thing to be hotting up. House price indices report annual growth across the board. Nationwide July House Price Index reports a 1.5% annual increase in house prices and a monthly increase of 1.7% Halifax July House Price Index reports a 3.8% annual increase and a monthly increase of 1.6%. Rightmove July House Price Index, based on asking prices, reports a 3.7% annual increase.