Spain experiences three climatic types: continental, maritime, and Mediterranean. The locally generated continental climate covers the majority of peninsular Spain, influencing the Meseta Central, the adjoining mountains to the east and the south, and the Ebro Basin. A continental climate is characterized by wide diurnal and seasonal variations in temperature and by low, irregular rainfall with high rates of evaporation that leave the land arid. Annual rainfall generally is thirty to sixty-four centimetres; most of the Meseta region receives about fifty centimetres. The northern Meseta, the Sistema Central, and the Ebro Basin have two rainy seasons, one in spring (April-June) and the other in autumn (October/November), with late spring being the wettest time of the year. In the southern Meseta, also the wet seasons are spring and autumn, but the spring one is earlier (March), but the autumn season is the wetter one. Even during the wet seasons, rain is irregular and unreliable. Continental winters are cold, with strong winds and high humidity, despite the low precipitation. Except for mountain areas, the northern foothills of the Sistema Iberico are the coldest area, and frost is common. Summers are warm and cloudless, producing average daytime temperatures that reach 21 ˚C in the northern Meseta and 24 to 27 ˚C in the southern Meseta; the night time temperatures range from 7 to 10 ˚C. The Ebro Basin, at a lower altitude, is extremely hot during the summer, and temperatures can exceed 43 ˚C. Summer humidities are low in the Meseta Central and in the Ebro Basin, except right along the shores of in the Rio Ebro where humidity is high.