“October is the coloured month here,” wrote Nan Shepherd in The Living Mountain, her meditative hymn to the Cairngorms. For me, it seems a month that grasps the whole spectrum of colours in its eager hands before November winds blow them away and December darkness falls.

The great oaks still hold most of their leaves and are mostly still green, though tinged with yellows and browns. The birch leaves are a soft shower of lemon and lime, gradually thinning to reveal more of the cross-hatched white trunks and the spindly black branches. The aspens, meanwhile, are the showgirls of the forest, shimmying in cascades of gold to the rustling of their own applause. Their castoffs carpet the trails, each leaf brightly splashed as an artist’s palette before being crushed into the mud.

In the forest, the solitary rowans do their own thing. Some are still verdant with feathered green leaves and fat bunches of berries, red as postboxes. Others have gone bald early, their fruit blackening, while others have sunny yellow clusters set against leaves turning scarlet. On the tier below, the dying bracken is shifting from gold to copper to bronze, while further down on the woodland floor, the mosses thrive in fresh, immodest greens, fungi sprouting among them, wildly strange in colours of temptation and poison.

At the edge of the trees, the river holds the sky, sometimes grey as doves, or gunmetal, or silver, sometimes blue as a dream. Moody days of darkness and fleeting rain are transformed by rainbows, light piercing the water veils to refract and reflect in hues so luminous that we are stopped.

Beyond the river, the fields are dotted with cattle and geese, the grass glowing in the low sun till it meets the border of deep evergreen forest. Beyond that, the hills. Their curving flanks change colour with every mood of the weather, and never more so than in October, with the radiant dying of foliage and the coming of storms.

These hills are “most opulently blue when rain is in the air”, said Shepherd. Today they are a brooding indigo as cloud foams off the Cairngorms plateau like a cauldron. High on the tops, the dark mountains are speckled white with the first of winter’s snow.