The climate throughout the Mediterranean Basin is relatively the same although temperatures in the east are warmer than those in the west. The temperature of the water at the surface has risen in recent years because of the greenhouse effect. Because the Mediterranean is a relatively small sea, it warms much faster than the larger bodies of water. Off the coasts of Israel and Egypt, the sea warms to 31° Celsius in the summer and cools to 16° Celsius in the winter. In the western portion of the Mediterranean, summer water temperature reaches 26° Celsius and in the winter drops to 11° Celsius.
The climate in the eastern Mediterranean Basin is characterized by hot, dry summers and cold, rainy winters. The summer coastal areas are extremely muggy in the summer but temperatures there are milder than inland. Winter temperatures near the coast are also milder than inland.
Two major weather systems affect the Mediterranean Basin: cold weather systems over Europe and the subtropical high over the desert areas to the south. In the summer, the subtropical high spreads northward to include southern Europe, causing hot, dry weather. This is pronounced in Israel. The subtropical high retreats in the fall allowing cold weather systems accompanied by rain to enter the Mediterranean Basin. High altitude troughs bring rain to Israel. Because of global warming, the subtropical high has strengthened. It arrives sooner in the spring and leaves later in the autumn. The result has been warmer temperatures and less precipitation throughout the Mediterranean Basin. The Mediterranean Sea is relatively small, so, when rain-bearing systems do develop they are shallower than systems over the open oceans where great storms such as hurricanes and typhoons develop. The geography of the Mediterranean doesn't allow such storms to develop. The rise in water temperature has led to a rise in surface temperature along the coasts. One degree increase in water temperature translates into a two-degree rise in air temperature. The rise in water temperature is expected to bring increased autumn rainfall to Israel's coastal areas.