13°C is cool — ideal for sleep depth. Research shows deeper slow-wave sleep in cooler bedrooms, as long as the room stays above about 16°C. If your bedroom drops below that, sleep quality starts to decline again.

Dew point is just 8°C — dry, fresh air. This is the kind of night where an open window does exactly what you want it to: brings in cool, comfortable air that helps your body maintain its natural overnight temperature drop.

A 5.1°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.