Migraine by Samuel Fisher

The snow has melted, but the thaw reveals a world transformed London is in ruins, its population a fraction of its pre-freeze level. The weather has become wildly unpredictable - huge pressure swings leading to powerful localised storms. And this has led to an epidemic of migraine. When a storm hits, the pain comes, along with a wide range of visual and haptic hallucinations named Migraine 'aura'. The novel starts with Ellis, one of a very small proportion of the population who don't suffer from weather-induced migraines, being struck by a migraine attack for the first time. After being blinded by hallucinations, he wakes in a ruined bookshop with its former owner, Sam, who pulled him to safety from the storm. No longer excluded from the migraine epidemic, Ellis decides to find his ex-girlfriend, Luna, and win her back. With Sam tagging along, he sets out from the bookshop and heads south.