The Sum of Our Days, by Isabel Allende, trans. Margaret Sayers Peden

Isabel Allende's memoir begins with the author lying wide awake on an exceptionally stormy Californian night. She is disturbed not, by the ferocious wind or the rain but, by a superstitious fear. For it is the eve of 8 January, the day on which for the past 25 years she has always begun the writing of a new book. She feels that if she starts on any other day, the work will be a failure.

All this is very typical of Allende, who,, by her own admission, inhabits a world full of melodrama, premonitions, omens and spiritual encounters. Her family history is so extraordinary that she needed to look little further for inspiration for the characters that make up such a fantastical saga as her first, most successful novel, The House of Spirits. Unsurprisingly, as she confesses, such a legacy made her unable for much of her life to separate fantasy from reality.

However, in 1992, reality impinged upon her dreaming in a way she called "intractable". Her daughter Paula, a victim of a rare genetic disease, fell into a coma from which she would never emerge. Allende, as a way of distracting herself during the many months of waiting in hospitals, started writing a long letter to Paula in which, for the first time, she candidly shared her past, which she likened to "an innermost garden... not even my most intimate lover has glimpsed".

The resulting book, Paula, proved therapeutic as well to thousands of readers, for whom Allende acquired something of the guru-like status of Paolo Coelho. As a portrayal of both filial loss, and a mother's intense relationship with her daughter, Paula has an emotional directness that is cathartic. It is also a fascinating portrait of Allende's early years, chronicling her upbringing in Chile, her disintegrating first marriage, and her exile to Venezuela following the event she considers the second great tragedy of her life: the Pinochet-led coup of 1973 which brought about the fall of her uncle Salvador.

The Sum of Our Days takes up the story of Allende's life from the time of her daughter's death, and is likewise addressed to her. After her turbulent existence, she has now come to enjoy a relative degree of stability with a new husband and life in California. From the pungent and bizarre reality of South America she has moved on to a world of Jacuzzis, Zen sessions, consultations with therapists and astrologers, and a committed membership of a women's mutual self-help group, The Sisters of Disorder.

As a happily married and hugely successful author with a taste for the New Age Californian lifestyle (described, by her without a trace of self-mockery), Allende could well have ended up producing a bland, self-satisfied autobiography padded with tales of glamorous engagements and meetings with other celebrities. Admirably, in compliance with her daughter's lack of interest in fame, she avoids that world almost entirely; and her only brush with the famous is an encounter with the cast of the film of The House of the Spirits. She is pleasantly surprised that Jeremy Irons proves not to be "a frosty aristocrat" but to have the character of a "likable taxi driver in the suburbs of London".

Once again, it is her family and eccentric circle of friends who provide her with her principal material. Though even The House of the Spirits succeeded in making several relatives refuse to speak to her afterwards, she has opted, as in Paula, for an unflinching frankness in her portrayal of these people. "If it comes down to choosing between telling a story and offending relatives," she says, quoting her agent Carmen Balcells, "any professional writer chooses the former." No wonder that her son Nico says that it is not easy to have a writer in the family.

She reveals her personal life in the most intimate detail, down to her every major row with her lovingly tolerant American husband, Willie; whom, we also discover, has written an "abominable" first novel. And she does the same with all the other members of what she calls her clan, most of whom she has cleverly managed to gather around her in California, so that perhaps she can study them more closely. Luckily for her, and for the reader, she is so close to her family that she can even go with her mother on a hunt for pornography in San Francisco's bookshops. Even more luckily, her relatives seem never to go long without suffering the most dramatic emotional crises. "Fortunately though", she comments after a session with a therapist, "the family melodrama continued, because, if not, what the devil would I write about?"

There are times when The Sum of Our Days reminds you of one of those ludicrously over-the-top but none the less compulsive Latin American soap operas. There is the exotic setting of a Chilean-style hilltop home inevitably dubbed The House of the Spirits; there is the interfering "mother-in-law from hell" (Allende herself); and there is the cast of unfailingly beautiful and passionate women. A climax of potential absurdity is reached when Allende is woken, by a telephone call while sleeping in a Maharajah's palace in India. Her formerly homophobic daughter-in-law, Celia, is on the line; and she is ringing to say that she is about to leave Nico and move in with stepson Jason's girlfriend Sally. She, we have previously learnt, has had a fling with Paula's widower, Ernesto.

The late Chilean writer Roberto Bolaño notoriously characterised Allende as "a scribbler whose attempts at literature range from the kitsch to the pathetic"; and doubtless he would have found further scope for his bile in The Sum of Our Days. Certainly, this memoir lacks the consistent power of Paula, and unwittingly conveys at times the loss of direction that Allende felt after her daughter had died. But, for the most part, the reader is swept along, by the energy of her prose, her brilliance as a story-teller, and the sheer force and warmth of her personality. Unlike Bolaño, a far more innovative author, she writes essentially from the heart; and this is the source both of some of her failings as a writer, and of her remarkable and well-deserved popularity.

Michael Jacobs's latest book is 'Ghost Train through the Andes' (John Murray)