Overview: CastelsardoCastelsardo (Italy) in general has a hot climate. The day temperatures range from 13 °C (55 °F) in January to 30 °C (85 °F) in July. The highest sea temperatures in Castelsardo are in August with 24 °C (76 °F) and the lowest in February with 13 °C (56 °F). Temperatures during the night go from 6 °C (43 °F) in February to 20 °C (69 °F) in August. The driest month is July with just 1 day of rain, on the contrary, the month when it rains the most is November with 11 days of rain.