Regnperiod

Regnperiod is a term used in meteorology, hydrology, and agriculture to denote a span of time during which a region experiences a notable and persistent amount of rainfall. The exact definition varies by region and literature; in many contexts it is effectively synonymous with the rainy season or wet season. It describes the part of the year when precipitation is concentrated and more frequent than in other periods.

Definitions of a regnperiod typically rely on rainfall thresholds or on rainfall totals over consecutive weeks or months. For example, it may be defined as a period in which daily or weekly rainfall exceeds a local threshold on a majority of days, or as a multi-month stretch during which monthly rainfall remains above long-term normals. The boundaries of a regnperiod can shift from year to year.

Causes and variability are largely linked to regional climate systems. Monsoon circulations, the west and south Asia ITCZ, tropical cyclone activity, and the position of storm tracks all influence the onset, duration, and cessation of a regnperiod. Ocean–atmosphere variability, such as ENSO, and local factors like mountains and plateaus, modulate its intensity. Climate change may alter regnperiod length and timing, with potential impacts on water supply and flood risk.

Measurement and data for regnperiods rely on rainfall records from weather stations and climatological normals, often supplemented by satellite precipitation estimates. In practice, regnperiod information informs agricultural planning, reservoir management, and flood preparedness by characterizing expected rainfall patterns within a region.