(ANSA) - ROME, JUL 31 - By Sunday 23 of the 27 major cities the Italian health ministry monitors for its heat warnings will be on the maximum red alert with temperatures set to keep rising as Italy's fourth heatwave of the year intensifies. On Friday 11 cities are on red alert - Bolzano, Campobasso, Civitavecchia, Florence, Frosinone, Latina, Perugia, Rieti, Rome, Turin and Viterbo. On Saturday the number will go up to 19 with Bologna, Brescia, Cagliari, Milan, Naples, Pescara, Venice, and Ve...