Hawaii's rainfall pattern is incredibly varied, with annual averages ranging from 204 mm (8 inches) near the top of Mauna Kea to 10,271 mm (404 inches). The Honolulu area experienced an average of 3.16 inches of rain in the month of February, according to their monthly total rainfall data. Interestingly, nearly all of Oahu's rainfall meters had a total rainfall that was higher than the average for that month. The amount of precipitation that falls on Oahu's farmlands can vary significantly depending on the location. For instance, the Koolau Mountains receive an average of 2,000 mm (79 inches) of rain per year, while the Waianae Mountains only get around 1,000 mm (39 inches).The season also plays a role in the amount of rain that falls on Oahu's farmlands.
Generally speaking, the months from November to April tend to be wetter than the months from May to October. During these wetter months, farmers can expect to receive an average of around 200 mm (8 inches) of rain per month. Overall, Oahu's farmlands receive an average of 1,500 mm (59 inches) of rain per year. This amount is slightly higher than the national average for Hawaii, which is 1,400 mm (55 inches).
