Short answer
Choose cloth for the places and seasons where you expect to wear these overcoats. Ask the tailor about fibre, weight, weave and care for the specific options; a city's name alone does not determine the right cloth.
Double-faced cashmere for the serious north, heavy flannel and wool–cashmere blends for the mid-winter cities, with storm details discussed in the room.
September serves four-season commissions; late-October fittings look straight to winter — heavier flannels, a cashmere overcoat conversation, and cloth for the ball season that follows.
The full cloth books span fresh open weaves through four-season high-twist to winter flannels and cashmere blends. Bring the tailor your calendar; the shortlist comes back two or three cloths wide.
The itinerary is a proposal: months are planned, dates and venues confirmed individually. Final quotations are confirmed in writing before you commit.