For most of us, particularly those staycationers at play on the storm-spun fields of Albion, the predicted barbeque summer of 2009 has been a disappointment.

The only demographic to feel some invigorating heat this year has been, of all groups, the poets. Carol Ann Duffy’s Poet Laureate appointment heightened interest in verse and versifiers just at the moment the BBC launched a major series of programmes on her tricky trade.

Ruth Padel’s involvement in a campaign to smear a rival candidate for the Oxford Professorship of Poetry election wasn’t exactly ennobling, but did at least remind the public that, far from etiolated wallflowers, some (most?) poets have beating in their chests the hearts of leopards. Into this humid atmosphere there now enters Don Paterson with his fourth and arguably finest collection of poems. The title? Typically Scottish, typically Paterson – it’s Rain.

His publisher, Faber, is billing Rain as his “most direct”, as if his previous volumes had been written in some sort of Rwandan dialect. They’re onto something, though. Meeting in Edinburgh’s Calton Hotel, in a bar as empty as a haunted house, I ask Paterson how he settles on a tone – in this case, a less playful, starker one – for a collection of poems.

“There are things going on in your life that end up getting written about more than others,” he says. “And there are times when there’s not much going on, so you make stuff up. Sometimes life comes along and provides you with subject matter, but whether that leads to you being more direct or not... I was more conscious that I was writing more directly, as I belatedly realised most people quite like that sort of thing. I asked myself, why do I keep returning to Robert Frost? I’m always touched by Frost, and I tried to figure out what he was doing, and a lot of it is to do with that direct address.”

I last met and interviewed Paterson five years ago, not long after his acclaimed third collection, Landing Lights, had won the TS Eliot Prize. Born in Dundee in 1963 into a house that was musical rather than literary, Paterson moved to London, aged 20, to pursue a career as a jazz guitarist. It was with poetry rather than music, however, that he was to pierce the public consciousness.

Since that last interview, Paterson has published two collections of aphorisms, The Book Of Shadows and The Blind Eye, while his Sonnets To Orpheus translated Rilke. He was awarded an OBE; he takes my joshing that this means he’s joined the Establishment in good spirit. He has also separated from his wife, which may in part explain the sombre, questioning atmosphere of Rain.

“I’ve been thinking things over, particularly this past five or six years.

My philosophical position has changed quite a lot.” In what way? “I’ve been getting hardcore materialist in some ways. I’ve been reading popular science, and thinking about the basis of stuff.

“I obsess about the way in which material elements have somehow conjured this madness up amongst themselves. You start with gas and end up with a blether in the Calton Hotel.”

Hardcore materialism, eh? This is something of a change. The pre-Rain Paterson took a Zen-Buddhist slant anchored to an self-punishing Calvinist inheritance (his grandfather was a United Free Church minister) and a contrasting interest in the carnal. Poems were often spiced by a Borgesian playfulness mostly absent from Rain. Paterson’s second collection, God’s Gift To Women, featured On Going To Meet A Zen Master In The Kyusha Mountains And Not Finding Him, a jeu d’esprit that amounted to a blank page. In Rain, there is another blank page, titled Unfold, the whiteness of the page in this instance chiming with the collection’s wintry ambience.

“It feels like a mid-life collection,” Paterson says. “I think, for that reason, the voice is closer to me than usual. Usually I refract myself through a variety of different voices. To me, the voice in this collection is more consistent.” Is he comfortable with that? “No, I’m not comfortable with it at all. Particularly that long poem at the end; I wasn’t comfortable at all with writing it.” The poem he references is Phantom, which is dedicated to the memory of his friend, the poet Michael Donaghy, who died at the age of 50. Donaghy had briefly performed with Paterson’s band, Lammas, and they often read together in public.

“I took his death pretty hard. We all did. I didn’t want to write that poem. Everyone else in the class had written their elegies, and I was still making excuses. I knew it had to come.”

In addition to movingly marking the passing of a friend, Phantom is unstinting in its depiction of the mixed emotions of the grieving artist. Paterson, channelling Donaghy’s voice, writes in it: “I knew the game was up for me the day/I stood before my father’s corpse and thought/If I can’t get a poem out of this/... Did you think any differently with mine?” According to Paterson, “Donaghy really did say that. And maybe I did think that when I was standing before his grave.”

Sounds tough on the heart, and it is, but the collection is also a bracing encounter with mid-life doubt elevated by the steely hold Paterson has on form.

And for fans of his old style, the collection has a standout poem that delights purely in its own engagement with recherché jargon, Song For Natalie ‘Tusja’ Beridze: “then no longer will all those gorgeous acoustic spaces/be accessible only via an offline procedure involving freeware convolution reverb and an imperfectly recorded impulse response of the Concertgebouw.”

We marvel at the way in which technical language can develop its own poetry, and Paterson admits to having been “infected” by the street-lingo of the cops and gangstas in the TV show The Wire. Paterson has, in fact, unimpeachable taste in televisual entertainment: he also praises The Larry Sanders Show and Battlestar Galactica. His dog, a poodle, is named Caprica Six after a BSG character. Worth bearing in mind when travelling through the oft-bare poetryscape of Rain.

Soon our time is up and we exit the hotel for Festival-fuzzed Edinburgh. The weather is dry, like Paterson’s sense of humour. I remember then something Paterson says by way of explaining the collection’s title. “I suppose – this is a bit sad – but poetry, like rain, falls out the sky.” In which case, you can keep your ­barbecue summers.

Rain is published on September 3 by Faber, £12.99