We have a term in Scotland for hot weather, known as "taps aff" (or in English: tops off). Referring to the act of removing one's shirt in the event of warm weather. The general consensus is anything above 15°C and sunny warrants the removal of clothing.
Bear in mind that the climate in Caledonia is roughly a baw hair away (yes, that's an official measurement in Scotland) from being submerged in the ocean.
I was in Kirkwall last year, and it hit 26°C there, and I was talking to a local at the bar. "I've lived here since 1987" he told me, "that's the first time I've seen it this hot".
