Use "Chance of Rainbow" to help find rainbows!
Type in a location, such as a city or restaurant, to see how likely you will see a rainbow there. This app predicts the rainbow percentage from 3 things: Precipitation (chance of rain), cloud coverage, and time of day. You will be more likely to see a rainbow if there is a lot of rain, a lot of sun, and if the sun is at an ideal angle in the sky (not directly overhead).