Because the crowds go home, the sea reaches its warmest and the valley turns gold. September and October are, for our money, the two best months to be in Green Spain on your own: the weather softens rather than collapses, the hosted weeks keep running, and everything from mountain trails to market towns grows quieter by the day.

What is the weather honestly like?

Early autumn is often the most settled spell of the year here. September can string together warm, clear days that August never quite promised, and October usually stays mild even once the showers return. Usually — this is the green north, and the green is paid for in rain, so bring a waterproof you trust and expect to wear it once or twice. The full month-by-month picture is in Cantabria weather by month; the short version is that you will walk most days and be glad of the fireside on one or two evenings. Daylight does shorten through October, so the bigger walks start earlier; nobody seems to mind, since the light at either end of the day is the best of it.

What changes in the Saja valley in autumn?

Two things worth planning a trip around. The beech woods of the Saja-Besaya reserve begin to turn, and by mid-October the slopes above the house run copper and gold; autumn colour in Green Spain makes the fuller case for coming just to look at trees. And the berrea begins — the red deer rut, when stags bellow across the valleys at dawn and dusk. Heard from a quiet track in half-light it is one of the great free spectacles of the Spanish autumn, and there is a whole week built around it: see the deer rut in Saja-Besaya.

The walking improves in a practical sense too. The forest routes above Ucieda stay under 600 metres, so early-autumn weather rarely troubles them, while the Puertos de Sejos — over 1,000 metres and honestly hard — are best claimed in September, before the high ground shuts up shop for the year.

Is the coast still worth the trip?

Very much so. The Bay of Biscay holds its summer warmth late, so the sea is at or near its warmest of the year in September, just as the beaches empty. The surf beaches sit about forty minutes from the house, and this is a kind season to learn in; surfing in Cantabria for beginners explains what a first lesson actually involves. For a gentler sea day, the flat coastal path at San Vicente de la Barquera gives you around eleven kilometres of salt air, and October light flatters every yard of it. The towns change character too — Santillana del Mar in October is a different place from its August self, quiet enough to hear your own footsteps on the cobbles.

Are hosted weeks still running that late?

Yes — autumn is part of the main season here, not an afterthought. Walking weeks (Walkwise runs those) continue through both months, and September and October also suit the quieter themes: painting, when the woods do half the work for you; yoga; riding, including low-tide rides along freshly emptied sand. Every week stays hosted and escorted, with half board, home cooking from the garden and one long shared table, exactly as in high summer.

Why do these months suit solo travellers in particular?

Partly value: prices are often gentler outside high summer — there's a separate piece on why the shoulder season suits a solo walking week. Partly ease: airports, ferries and roads all calm down once the school holidays end, which takes the edge off travel days when there is nobody to share them with. And partly company: the people who choose September and October tend to be unhurried — retired, semi-retired or simply flexible — and the groups that gather round the table in autumn are some of the easiest of the year.

Booking works the same as ever. You join a scheduled week as an individual, with no forced single supplement: twin-share with a same-sex room-mate at no extra charge, the supplement covered if no match is found, or a room of your own for an optional supplement. Weeks are booked through Spice Escapes, Casa Agara's exclusive booking partner, who also run city breaks and other hosted trips through the autumn if these dates or this valley do not fit.

What should you pack differently?

Layers rather than bulk. A dependable waterproof, something warm for berrea dawns, and swimwear regardless — the sea in September will likely be warmer than anything you swam in at home all summer. Boots already walked in, never new. The complete list, surf kit included, is in what to pack for walking and surf in Green Spain.

If an autumn week appeals, the scheduled holidays are here — and Rob and María can tell you which dates should catch both the colour and the berrea.