Thresholds of Winter

This visualization maps daily minimum and maximum temperatures in Central Park across more than a century, rendering climate as a dense field of seasonal repetition and disruption. Each row is a year, each column a day; read together they reveal long-term patterns that are otherwise difficult to perceive: persistent cold, extreme heat, and shifting thresholds.

An interactive filter isolates days above or below a selected temperature limit — winter chill, hot nights, heatwaves — so the picture holds thresholds and duration rather than averages. Those are the conditions that govern plant dormancy, urban ecology, and lived experience in New York City: a chilling requirement met or missed, a run of nights that never cools.

The spring arrival line estimates when spring-like conditions first appear each year, taken as the first day the daily maximum reaches or exceeds 60°F (15.6°C). The shift toward earlier emergence appears as the line drifting leftward through time.