The best novels, like the weather, are unpredictable. In two recent releases, Maggie O’Farrell’s much-anticipated sixth novel, Instructions for a Heatwave, and Anna Stothard’s The Art of Leaving, two very different London summers mirror the unsettled lives of their inhabitants, from stifling, oppressive heat to drizzle which alternately threatens to become a downpour or to stop completely but never quite commits to either.

Ironically for a book so concerned with the early fizz, flare and eventual fading away of promise, Anna Stothard’s third novel cements her place as one of Britain’s best young authors. In The Art of Leaving, Eva Elliott believes she has created a life with no ties except her attachment to her grandmother’s old flat. In reality, she spends her days in a job she drifted into and now seems unable to leave, and her nights with Luke, the boyfriend she is constantly plotting to dump but never can. Her fantasies of another life are fuelled when Regina, a golden eagle, escapes from her cage and her mate in London Zoo, and spends the summer wheeling across the city sky. A chance encounter with a woman at a party – beautiful, impulsive, chaotic Grace – invigorates Eva. But Grace’s intentions are not straightforward.

Stothard’s lush, dreamy prose is given full rein during Eva’s frequent flights of fancy about the lives of the women in the strip club over the road in a style reminiscent of Angela Carter. When Eva’s life starts to unravel, she sees that the narrative she has woven around conventional, self-possessed Luke falls as far short of reality as her elaborate fantasies in which underage strippers become magicians’ assistants and a seedy doorway in Soho leads into another world. It would be easy for the realistic elements of the novel to feel drab in comparison, but Stothard luxuriates in the detail of Eva’s world, locating her in a microcosm of the publishing industry that avoids the usual solipsistic clichés. The bird metaphor, too, is skilfully handled: Eva is uncomfortably aware that her interest in Regina reflects her increasingly panicked sense of claustrophobia; but the parallels between the bird of prey and Eva’s own latent predatory instincts are left for the reader to pick up on.

In Instructions for a Heatwave, Gretta Riordan’s husband goes out to buy a newspaper. When he doesn’t return, past transgressions resurface, old arguments are raked over and family secrets are revealed. The stultifying heat adds to the sense of oppression as Gretta’s three children find themselves drawn back to their childhood home.

Gretta’s daughter Monica has the perfect life: a beautiful old farmhouse immaculately restored by her antique-dealer husband; beautiful stepdaughters who only live with them at the weekends; and a closer relationship with her mother than either of her siblings. But beneath her calm surface lies seething resentment – at her husband and his impractical, old-fashioned house; at her stepdaughters, who remain stubbornly indifferent to her; and especially at her sister, whose birth triggered the post-natal depression from which Gretta has never entirely recovered and whom Monica blames for the disastrous end of her first marriage.

Michael Francis, the second child and a frustrated academic turned schoolteacher, is clinging on to the shards of his marriage following an intense but short-lived affair that has left his wife unsatisfied with her domestic life. Monica’s sister, Aoife, an undiagnosed dyslexic, has spent her life carving out an independent existence away from her family and hiding the fact that she has never learned to read. Working as a photographer’s assistant in New York with a mounting pile of paperwork which she is unable to deal with, the news of her father’s disappearance affects her deeply.

Gretta’s bitter regret at her children’s rejection of their Irish heritage and Catholic upbringing has its roots in the secret she has kept from her children – and, to an extent, herself – all their lives. O’Farrell is at her best teasing out the tangled history of a marriage where truth and deception intertwine, but Instructions for a Heatwave offers much more than a portrait of a family in crisis. It deals with identity, both national and personal, the way we reconstruct ourselves and the shameful parts we keep secret but which never entirely disappear.