seasonal

Seasonal is an adjective that describes things related to the seasons of the year or to recurring patterns tied to particular times within the year. In weather and climate, seasonal patterns refer to predictable changes in temperature, precipitation, daylight, and wind that occur in a regular cycle across the year, with distinct patterns in temperate, tropical, and other climates. In agriculture and food, seasonal products are those that are harvested or produced during specific times of the year; markets, menus, and recipes often reflect seasonality.

Seasonality also affects economic activity and data, as holidays, school calendars, weather, and cultural events create regular fluctuations in demand and supply. Economists use seasonal adjustment techniques to remove these effects from statistics to reveal underlying trends. In labor markets, seasonal work peaks in agriculture, retail, tourism, and construction.

Seasonal affective disorder is a mood disorder associated with seasonal changes, typically worsening in winter months for many individuals; symptoms can include low mood, fatigue, sleep disturbances, and social withdrawal. Treatments include light therapy, psychotherapy, and medications when appropriate.

Culturally and commercially, seasonality shapes fashion, advertising, tourism, and entertainment, driving seasonal collections, peak travel periods, and holiday programming. In ecology and biology, many species time key life-history events to seasons, such as migration, flowering, breeding, and dormancy, guided by cues like day length and temperature. Climate change can alter the timing and intensity of seasonal cycles, with wide-ranging ecological and social implications.