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Your sky
The live map centres on you and scores the places around you where someone could actually be, hour by hour, seven days out, with a reason for every number.
Open the mapWorldwide rainbow forecast
The odds of a rainbow, anywhere on Earth, hour by hour.
Bowcast reads live ensemble weather through the optics of how a rainbow actually forms, then tells you the chance of seeing one around you, or shows you where on the planet one is most likely this very hour.
A rainbow is geometry plus weather, and Bowcast computes both.
Geometry fixes the bow at 42 degrees from the point opposite the sun. Weather decides whether sunlit rain is sitting in that patch of sky. A Monte Carlo over about forty ensemble members turns the forecast's uncertainty into an honest probability. Every threshold is drawn from published atmospheric-optics research, and the scoring engine is roughly 450 lines of dependency-free code you can read.
Read the physics, with the equations02
The whole planet
Every one of the world's rainbow capitals, ranked by this hour's odds, with a live webcam pointed at the sky where a bow is most likely right now.
See rainbows now03
The craft
Field guides to where rainbows cluster, when to look, and how to photograph one before its five to thirty minutes are gone.
Read the guidesRainbows give you minutes, not hours. Bowcast is for catching them.
Open the map