The setting has a profound effect on the characters in "Searching for Summer" in that it encourages them to keep looking for the merest hint of sunshine.
The story is set in a postapocalyptic Britain where there is little or no sunshine and where blue skies are the stuff of old people's stories. Some kind of nuclear conflict appears to have taken place in the none-too-distant past that has made everything so grey and drab and dull.
Yet that doesn't stop people from searching for sunshine. Whenever there's an announcement on the radio that the sun is shining over such-and-such a place, people head there in droves, desperate to catch a glimpse of what has become an incredibly rare natural phenomenon.
The rare appearance of that hot orangey thing in the sky makes it all the more special for newlyweds Tom and Lily when they are bathed in beautiful sunshine on their honeymoon, not to mention the silvery gleam of starlight, another rarity in this post-nuclear landscape.