Edinburgh vs Reykjavik
Re-score for me — drag the dial — every chart on the page recolours live for your heat limit 27°C
Default 27 °C is the upper edge of the Holiday Climate Index "ideal comfort" band (Scott, Rutty, Amelung & Tang, 2016). Above this, most warm-tourism travellers report measurable discomfort.
Edinburgh peaks in June, September, August (annual avg 4.6/10). Reykjavik peaks in July, August, June (annual avg 2.8/10).
Edinburgh upper vs Reykjavik lower
Reykjavik. Visit June through August for the long days (18+ hours of light) and the only window when the highlands open, hiking is feasible, and the road into the interior is passable. February and March are peak Northern Lights season — short days, real cold, but the sky is dark enough and the activity is high. September is a defensible shoulder month for both daylight and aurora. November through January is the quietest and the rawest: most outside-the-city activity is dialled down and weather is genuinely difficult.