Thanks to the great longitudinal extension of the peninsula and the mostly mountainous internal conformation, the climate of Italy is highly diverse. Conditions on peninsular coastal areas can be very different from the interior’s higher ground and valleys, particularly during the winter months when the higher altitudes tend to be cold, wet, and often snowy. The coastal regions have mild winters and warm and generally dry summers, although lowland valleys can be quite hot in summer. Average winter temperatures vary from 0 °C (32 °F) on the Alps to 12 °C (54 °F) in Sicily, like so the average summer temperatures range from 20 °C (68 °F) to over 25 °C (77 °F). Winters can vary widely across the country with lingering cold, foggy and snowy periods in the north and milder, sunnier conditions in the south. Summers can be hot and humid across the country, particularly in the south while northern and central areas can experience occasional strong thunderstorms from spring to autumn.