21°C is above the ideal 16–18°C range, but not dramatically. Most people will still fall asleep — it's staying asleep through the early hours that becomes harder, because your body can't complete its natural cooling cycle.

Dew point is 15°C — not extreme but enough to make the warmth feel stickier than the temperature alone suggests. The gap between temperature and dew point is what determines whether the air feels fresh or muggy.

A 5.5°C drop between bedtime and 4am is substantial. This natural cooling aligns with your circadian rhythm — your body temperature dips in the early hours, and the environment cooling alongside it produces the deepest sleep of the night.