Honolulu experiences a tropical semi-arid climate (Köppen classification BSh), with a mostly dry summer season, due to a rain shadow effect. Temperatures vary little throughout the months, with average high temperatures of 80–90 °F (27–32 °C) and average lows of 65–75 °F (18–24 °C) throughout the year. Temperatures reach or exceed 90 °F (32 °C) on an average 38 days annually, with lows in the upper 50s °F (14–15 °C) occurring once or twice a year. The highest recorded temperature was 95 °F (35 °C) on September 19, 1994 and August 31, 2019. The lowest recorded temperature was 52 °F (11 °C) on February 16, 1902, and January 20, 1969. With high temperatures and humidity all year, Honolulu’s climate is sometimes described as tropical, but according to the definitions of the Köppen classification, it falls short of being truly tropical because of its low annual rainfall.
The annual average rainfall is 17.10 inches (434 millimeters), which mainly occurs during the winter months of October through early April, with very little rainfall during the summer. However, both seasons experience a similar number of rainy days. Light showers occur in summer, while heavier rain falls during winter. Honolulu has an average of 278 sunny days and 89.4 rainy days per year.
Although the city is situated in the tropics, hurricanes are quite rare. The last recorded hurricane that hit near Honolulu was Category 4 Hurricane Iniki in 1992. Tornadoes are also uncommon and usually strike once every 15 years. Waterspouts off the coast are also uncommon, hitting about once every five years.
Honolulu falls under the USDA 12b Plant Hardiness zone.
The average temperature of the sea ranges from 75.7 °F (24.3 °C) in March to 80.4 °F (26.9 °C) in September.