Interannually

Interannually is an adverb used to describe measurements, comparisons, or changes that occur from one calendar year to the next. It is commonly used in statistical reporting to indicate year-to-year movement.

It is formed from inter- meaning between and annus meaning year. The related adjective interannual describes phenomena that vary from year to year, while interannually describes how a measurement or comparison is reported or observed.

In economics, finance, demography, and climatology, interannual analyses are standard. They may express growth rates, inflation, consumption, or rainfall as percentages relative to the prior year. In climate science, interannual variability refers to year-to-year fluctuations in temperature or precipitation, often linked to atmospheric patterns such as El Niño or La Niña.

The term is closely related to year-over-year (YoY) comparisons. Some writers use interannual and interannually interchangeably with YoY, while others reserve "interannual" for comparisons that span entire years rather than within-year cycles.

See also interannual, year-over-year, data analysis, statistics.