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Honolulu, the capital of Hawaii, sits on the southeastern shore of the island of Oahu in the central Pacific, sheltered in the lee of the Koolau range at approximately 21.31°N, 157.86°W. It has a tropical semi-arid climate (Köppen As/BSh) — warm and remarkably steady year-round, cooled by the trade winds — and it is far drier than the windward side of the island.
There is no summer in the temperate sense: temperatures barely change, with daytime highs around 30–31°C in the warmest months and warm nights near 23–24°C, tempered by the reliable northeast trade winds. Rain is scarce and brief; the dry season runs from May to October, and hurricanes occasionally approach the islands in late summer, though direct strikes are rare.
There is no true winter, but the wetter season runs from November to March, when highs ease to around 27–28°C and nights near 19–20°C. Rain increases as Kona winds — blowing from the southwest instead of the usual dry northeast trades — funnel moisture toward the islands, bringing heavier, more prolonged rain than the brief trade-wind showers.
Honolulu is dry, receiving only around 430–560 mm of rain a year, concentrated in the winter months from November to March; the trade winds drop their moisture on the windward Koolau slopes just a few kilometres away, which receive several thousand millimetres a year. Live rainfall, humidity, and pressure readings for the city are shown in the panels above.
Oahu's Koolau range creates one of the sharpest rainfall gradients on earth: Honolulu, in its lee, is sunny and semi-arid, while the windward slopes just over the ridge are drenched rainforest. The city's wetter winters are driven by Kona winds, which reverse the usual trade-wind flow and funnel moisture straight at the islands.
To follow any single measurement in Honolulu more closely, use our live instruments: the online barometer for atmospheric pressure, the thermometer for temperature, the hygrometer for humidity, the anemometer for wind speed, the wind vane for wind direction, and the rain gauge for rainfall.