Rainbow forecast for Hilo
Hilo, Hawaii, United States: today's peak estimated rainbow chance, the best forecast interval to look up, and the week ahead.
Rainbow weather in Hilo
Hilo sits in a trade-wind belt, where small, well-spaced showers can move through with sunshine between them. That changeable pattern often supplies the sunlit rain a rainbow requires. Mornings and late afternoons, when the sun hangs low, are useful times to watch.
At 19.7° north, Hilo's midday sun often climbs above the geometry for a visible primary bow. Early morning and late afternoon are the most dependable viewing windows through much of the year.
Wherever you are, the geometry is the same: a primary rainbow forms opposite the sun while the sun is less than about 42 degrees above the horizon. Bowcast's research-informed heuristics give extra weight to clearing showers. The gauge above applies them to ensemble forecasts for the 12 km around Hilo.
Rainbow questions, answered
- When do rainbows appear in Hilo?
- Rainbows need sunlit rain with the sun lower than about 42 degrees, so in Hilo useful windows often occur after sunrise or before sunset on showery days. A study in ZhaoSu, China found that about nine in ten observed rainbows occurred during the hour after rainfall. Bowcast uses that regional finding as research guidance, not a universal rate.
- Where should I look for a rainbow in Hilo?
- Always directly opposite the sun: put the sun at your back and look toward the retreating rain. In the evening that means looking east; in the morning, west.
- What is the estimated rainbow chance in Hilo today?
- Bowcast checks about 40 forecast ensemble members for sunlit-rain ingredients around Hilo, hour by hour, for the next 7 days. The result is an estimated chance from model agreement, not a probability calibrated against observed rainbow frequencies. This page shows today's peak and best forecast interval; the Now board shows the interval containing the current time.
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