Hilo's drive-up falls on the Wailuku River, 80 feet over a lava cave said to be the home of Hina, and named for the rainbows in its morning mist.
November through April
Big water window
in a typical year
Rain fed
What drives it
Wailuku River
Live USGS
Data on this page
gauge 16704000
Hawaii State Parks
Managed by
their rules govern
Trail status, closures and safety rules belong to each falls' managing agency, named and linked on every page.
The season
What fills Rainbow Falls, and when
The Wailuku is Hawaii's longest river, draining the wet saddle between Mauna Kea and Mauna Loa, so Rainbow Falls responds within hours to Hilo rain: a broad brown torrent after storms, a pair of clean white ribbons in drier stretches. The morning rainbow the park describes needs sun and mist together, which the wet season supplies most reliably.
Typical best flow: November through April
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What the agency itself says
The 80-foot Rainbow Falls is renowned for the rainbow formed from its mist many mornings. Legends say that the cave beneath the waterfall was the home of Hina, mother of the demigod Maui.
Gauge: USGS 16704000 Wailuku River at Piihonua HI, upstream of the falls on the same river, above Hilo. The gauge reads the river, not the brink of the falls, so treat it as the trend line rather than a turnstile.
Source: USGS Water Services (National Water Information System). Instantaneous values and daily statistics services. U.S. Geological Survey data are works of the United States Government and are in the public domain. Gauge verified 2026-08-27.
Rain-fed falls carry the color of their watershed: Blackwater Falls runs amber with tannin from spruce and hemlock bogs upstream, and its volume tracks the last month of Appalachian weather. “Blackwater Falls (15437499241)” by Benjamin Smith from United States, CC BY 2.0
Getting there
Access, in the agency's words and ours
The falls overlook is open daily 7 am to 5:30 pm with gates locked at 6, per the state park. As of January 2026, parking and entrance fees apply to non-residents, covering both Rainbow Falls and the Boiling Pots unit upriver; Hawaii residents are free with ID.
The reliable big-water window is November through April. The Wailuku is Hawaii's longest river, draining the wet saddle between Mauna Kea and Mauna Loa, so Rainbow Falls responds within hours to Hilo rain: a broad brown torrent after storms, a pair of clean white ribbons in drier stretches. The morning rainbow the park describes needs sun and mist together, which the wet season supplies most reliably.
This page reads the USGS gauge on Wailuku River (Wailuku River at Piihonua HI, upstream of the falls on the same river, above Hilo) live in your browser, and shows the latest flow next to the median USGS publishes for today's date, so you can see where today sits in the year. The gauge reads the river, not the brink, so treat it as the trend rather than a turnstile.
It can thin to modest ribbons during dry spells, and thunder at flood stage a day later; the upstream gauge on this page shows which Wailuku you are getting. Mornings after rainy nights are the rainbow lottery's best odds.
Wailuku River State Park (Hawaii DLNR Division of State Parks). The falls overlook is open daily 7 am to 5:30 pm with gates locked at 6, per the state park. As of January 2026, parking and entrance fees apply to non-residents, covering both Rainbow Falls and the Boiling Pots unit upriver; Hawaii residents are free with ID. Trail status, closures and safety rules are theirs, and their page is linked on this one; nothing here overrides what they publish.
Yosemite Falls in May, running on snowmelt that will be gone by late summer. The National Park Service tells visitors the falls can be dry by August, which is why every falls page here starts from its watershed. “Tourists below Yosemite Falls (39832011431)” by Mike McBey, CC BY 2.0
Kauai's easiest great falls: a roadside overlook above the Wailua River valley, with the falls splitting and rejoining across its basalt lip as the rain dictates.
The double falls at the end of Maalo Road made famous by television, pouring off the South Fork Wailua and swelling into a single curtain after Kauai rain.
Places to stay