Rome, July 31 - Italians were heading for the gelato shop, swimming pool, the beach and even public fountains as the temperatures continued to sizzle and forecasters warned Wednesday of even more heat to come. A third blistering heat wave was forecast to blow up the peninsula from Africa, reaching the mainland by Friday and Saturday, bringing hot days and "sultry" nights, according to experts. The blast will hit north-central Italy, particularly centres including Bologna and Verona, especially hard with highs reaching 38 degrees C, according to web portal meteo.it. Humidity is also expected to rise, making temperatures feel as if they're above 40 degrees C in the north-central area along the Po Valley. The mercury could rise as high as 37 degrees from Trentino-Alto Adige to Veneto, Lombardy, Emilia Romagna, and down through Lazio, Tuscany and Campania while also reaching across to Sardinia. And for the rest of this week, Rome is under a red alert for heat, with warnings that high temperatures could be dangerous to the health of many, particularly the young, the elderly and those with chronic illness. This will be the most long-lasting and hottest stretch of the summer – so far, said meteorologist Francesco Nucera of 3bmeto.com. And it is going to hurt because of rising humidity and little wind to circulate air, he added. "Until now, this was not a particularly hot summer - nothing compared with 2012," he said. But weather patterns are changing, making high-pressure African weather systems more prevalent in the Mediterranean regions, added Nucera. "Blame African pressure systems - for the third time this season, they will return to roar through the Mediterranean".