Ask ten travelers when to visit Portugal and most will say “spring or fall” and leave it there — which is true, but it flattens a country that actually holds three distinct climates inside a space roughly the size of Indiana. Lisbon and the Algarve bake…

Switzerland doesn’t have a bad time to visit so much as it has very different Switzerlands depending on when you land. The lakeside cities and the high Alps run on almost separate climate calendars — Zurich can be shirtsleeves-warm in early May while Zermatt, an hour…