Holiday Weather. The warmest day over the next 7 days in Sicily is forecast to be 17th April at 18°C (64°F) and the warmest night on 18th April at 9°C (48°F). The average temperature over the next 7 days is forecast to be 14°C (57°F) and there will be 6 days of sunshine . The average for April is 12°C (53°F) in Sicily.