The region of Palencia has a Continental Mediterranean climate with very cool winters, due to altitude (749 m) and isolation from maritime influences, chilly winds, including some days of snow in the winter and minimum temperatures usually below 0 °C (32 °F). Fogs are also frequent because of the Carrion river. Summer tends to be warm with temperatures that consistently surpass 30 °C (86 °F) in July and that can rarely reach 38 °C (99 °F). Due to Palencia's altitude, nightly temperatures tend to be cooler, leading to a lower average in the summer months. Precipitation levels are moderated, but precipitation can be observed throughout the year (except July and August). Summer and winter are the driest seasons, with most rainfall occurring in the autumn and spring.[14] The rain is very frequent in winter, and infrequent in summer. Rainfall is light but frequent during the winter months, and infrequent in summer with heavy thunderstorms. The snow is an unfrecuently and light phenomenon at the city. It usually falls some days per year, during December, January and February, but it´s common watching some snowfalls during November or March.