regntiden

Regntiden, or the rainy season, is the annual period during which a region experiences persistent and intensive rainfall. The term is widely used in tropical and subtropical climates to denote a distinct contrast with a dry season. In these regions, rainfall is not uniform throughout the year but concentrated in one or more stretches of weeks or months, driven by large-scale atmospheric circulation rather than random showers.

Causes and timing: The onset and duration of regntiden are linked to the seasonal migration of the Intertropical Convergence Zone and to monsoon systems. Ocean–atmosphere interactions, such as El Niño and La Niña, can modulate intensity and duration from year to year. The length of the rainy period varies by region—from a few weeks to several months—and even within a country there can be multiple wet phases.

Regional patterns: In West Africa and parts of East Africa, regntiden shoulders the annual agriculture cycle, bringing essential rainfall for crops but also posing flood risks. In South Asia and Southeast Asia, the southwest monsoon brings several months of rain; in Central America and the Caribbean, tropical cyclones and monsoonal flows contribute to the wet season. The concept is used by meteorologists, agronomists, and planners to assess water resources and climate risk.