After a wet summer, T-shirt weather arrives in October. It’s the kind of balmy end-of-season Saturday afternoon that seaside ice-cream vendors surely must pray for. The clifftop car parks are filling up fast. People are drawn to this stretch of coastline to breathe clean, salty air along the promenade, play on the beach, enjoy a spot of sea angling or appreciate panoramic sea views that stretch from Tyneside in the north to Cleveland’s cliffs in the south. We’ve watched dolphins along this shore recently, but today there are none, only an inquisitive grey seal, surfacing close inshore. Sea glass collectors on Blast beach – heads down, searching for treasure – don’t notice the watcher, who vanishes in a swirl of sparkling wavelets. We leave the throng behind and follow the cliff edge path towards Hawthorn Dene, hoping to see a local early autumn wildlife spectacle: vast flocks of goldfinches, feeding on wildflower seeds in the limestone grassland. We can hear their chatter, but don’t see them until they are spooked by a jogger. Whoosh! At least 200 pairs of gold-barred wings take flight in communal panic. The flock rises and falls in unison, as if bouncing on air, wheels left then right, doubles back in our direction and streams in to settle on meadowsweet seedheads. These birds seem permanently exuberant; their excitement is infectious. We strike gold again near Hawthorn Dene, where fields of sunflowers are still in bloom. Wild bird seed cover crops, of fodder radish, quinoa and sunflowers, have been planted here in recent years, providing nectar for insects in summer and seeds for finches and reed buntings in the “hungry gap”, when the supply of food from native plants dwindles. By midwinter last year, trees around these acres were weighed down with vast flocks of linnets, sustained by supplementary feeding. It’s a golden afternoon, but there seems something surreal about sunflower crops on the Durham coast, a hint of Provence on the edge of the normally chilly North Sea during yet another year of record-breaking high temperatures. Maybe we should make the most of days like this, before winter comes, but there’s an underlying shiver of unease. Country diary is on Twitter at @gdncountrydiary