Heat Capacity. Heat capacity is the amount of heat required to raise a system by 1 degree C in temperature. Water has a heat capacity about 4 times that of air; this means that a given amount of water needs about 4 times as much heat to raise its temperature as that needed to raise the temperature of an equivalent amount of air. In other words, it’s much harder to change the temperature of a given amount of water than it is to change the temperature of the same amount of air. For this reason, weather in coastal areas is often more moderate than weather at the same latitudes in inland areas: The higher humidity of the air near the oceans makes that air more resistant to temperature changes than the drier air farther inland. The high heat capacity of water means that the oceans are capable of storing and transporting a large percentage of the earth’s heat.