When rainbows appear

Dear Tom,
Do rainbows only come out in the summer (when it is warm)?
Sam Fortuna (age 5)
Dear Sam,
Rainbows can appear in the sky at any time of the year because temperatures
are not involved in their formation. Unfortunately, the sky conditions that
are necessary to produce rainbows rarely occur during the coldest part of
the year, and so we almost never see them in the period from November
through February.
A rainbow can form only when bright sunlight shines directly on water
droplets (like raindrops) and the observer is in the proper place to see it.
But in the winter, the usual situation when it is raining is a gray, gloomy
and solidly overcast sky with no direct sunlight. Breaks in the clouds that
let sunlight shine directly onto raindrops usually occur only with showery
rain such as thunderstorms, which are mainly warm-season weather events.