Standing on the balcony at the Grand Hotel, Eastbourne, where Claude Debussy finished off La Mer, it struck me that composers come in two seasons — winter and summer. The winter sloggers chip away come sleet, come shine, delivering a crisp new score in March for premiere in September.

Tchaikovsky was a winter symphonist. In summer, he lounged around his dacha or took a cultural tour of Europe. Stravinsky, by contrast, was a summer man, creating the white-nights Firebird in Rimsky-Korsakov’s dacha and posing stark-willy naked for a camera outside his banya, on the river jetty. Shostakovich, given a dacha by Stalin, gave it back when it was safe to do so under Khrushchev. He found the state was using the summer break to keep an eye on his progress.

Mahler needed to take physical possession of a landscape that resembled his childhood environment

Summer composers start with Beethoven, who would flee the Vienna heat to take the waters at Baden. When he was unable to compose while battling for custody of his nephew Karl, the spa at Baden twice relieved his creative block. In the summer of 1816 he wrote the 28th piano sonata, opus 101, gateway to his late works, and summer 1822 yielded the formidable Consecration of the House overture.

Beethoven was so at ease in Baden that he took his acolyte Anton Schindler and nephew Karl into his composing process, singing two themes he had just invented and asking them “which we liked the better”. Both! they cried, so Beethoven made the overture out of two tunes.

Summer loosens up even the stuffiest of composers. Brahms, overnighting in 1877 at Pörtschach on the Wörthersee, woke up a changed man. “The first day was so beautiful that I wanted to enjoy another one, and the second was so beautiful that I am going to stay for quite a while,” he told Clara Schumann. In all, he spent three fertile summers at Pörtschach, composing his violin concerto and first violin sonata, the long-awaited second symphony and much else besides, all in major keys. Grumpy Brahms was a much jollier chap puffing away beside a summer lake.

Dvorak spent the summer of 1893 among Czech emigrants in the town of Spillville, Iowa. He came away with his 12th string quartet and the draft of his last and loveliest symphony, From the New World. Leos Janacek spent ten summers sexually infatuated with a married woman, chasing Kamila Stösslova without submission from one Bohemian spa to the next. The rewards for his summer persistence were eternal: three operas, the Glagolitic Mass and two impassioned string quartets.

The archetypal summer composer was Gustav Mahler who, working full time at an opera house, had only June to August for symphonic thoughts. In 1893, Mahler took rooms at an inn on the Attersee in northern Austria and built himself a shed at the edge of the lake. “No need to look up there,” he told Bruno Walter, who was admiring the mountains, “I have composed them all away.” Seldom has a composer revealed a more sensitive secret. In order to touch his unconscious, Mahler needed to take physical possession of a landscape that resembled his childhood environment.

I have climbed Mahler’s peaks and swum his lake, though never across and back before breakfast as he did. He must have had phenomenal upper-arm strength from all that opera-conducting. His brick outhouse, source of the second and third symphonies, served for a while as a public toilet. Today it has been restored for tourists as a Mahler museum.

Once he became director of the Vienna Opera, Mahler built himself a villa in Carinthia, across the Wörthersee from Brahms. At first light he climbed a steep slope to his hut in the woods, followed two hours later by a housemaid with a breakfast tray. How she kept the coffee from spilling over the croissants I have never worked out.

Mahler was not undisturbed on holiday. A secretary came up twice a week from Vienna with cast changes, contracts to be signed and all the human chaos of an opera house. His wife and two small daughters made afternoon demands on his time as did his first lover, Anna von Mildenburg, who occupied the next villa. He allowed himself a beer to relax with at dinner. Over seven summers, he wrote four and a half symphonies and two song cycles.

The idyll ended with the death of his elder child from diphtheria in 1907. Mahler told Alma to sell the house and never returned. When I last visited, it was inhabited by a Japanese family.

His final summers were spent at Toblach in the Dolomites, gazing out over green valleys and glorious peaks that the doctors forbade him to climb. His heart muscle damaged and his marriage in disarray, Mahler wrote two more symphonies and Das Lied von der Erde. A visitor in June 1909 reported constant rain, “the clouds rolling down from the mountains into the Puster Valley; even so, he went out walking every afternoon.”

Summer, like all else in art, is an illusion. Composer, use it or lose it

The hesitant opening of the ninth symphony has often been said to represent Mahler’s faltering heartbeat, though cardiologists refute this. From my own soaking in Toblach, I imagine a symphonic squelch of ruined shoes and a bleak burst of sunlight. It was so cold in his composing hut that Mahler had to light a fire before he could start work. An eagle flew in one day, maybe a raven; it’s the kind of detail you remember when listening to the constricted terrors of Mahler’s confrontation with nature in the raw and his own mortality.

Summertime, not necessarily sunny and gay, may signify pain and death. Debussy began La Mer in August 1903 at his in-laws’ estate in Burgundy. By 1905, visiting Eastbourne where “the sea unfurls itself with an utterly British correctness”, his orderly life was in tatters. His first wife, Lilly, had shot herself after he ran off with wealthy Emma, and he was the talk of Paris for all the wrong reasons. Never had a man so needed to gaze on the grey permanence of the English Channel to find his equilibrium. Summer, like all else in art, is an illusion. Composer, use it or lose it.