säätilastot

Säätilastot, or weather statistics, are systematic records that describe the weather of a place over time. They summarize observations into numbers such as daily mean temperature, total precipitation, precipitation days, sunshine duration, relative humidity, and wind speed, as well as record highs and lows. They can be reported for various time scales—daily, monthly, yearly—and for different locations.

Säätilastot are produced from weather observations gathered by official weather stations and supported by radar, satellites, and other data sources. National meteorological services compile and publish these statistics, and they feed into international climate databases. In Finland, the Finnish Meteorological Institute (Ilmatieteen laitos, FMI) is the primary producer of climate statistics. Data are published as climate summaries, long-term series, and climate normals. A climate normal typically covers a 30-year reference period (for Finland, such periods span recent decades, with 1991–2020 used as a standard example). Anomalies compare current conditions with the normal period.

Common products include annual climate reports, monthly climate summaries, extreme-value lists, and regional climate tables. Säätilastot support risk management, planning, and research, including agriculture, energy demand forecasting, infrastructure design, and policy development. They also enable researchers to monitor trends related to climate change, such as warming, changing precipitation patterns, and variability in storms.

Data quality and homogenization: stations may move or be upgraded, requiring adjustments to ensure comparability over time. International standards from the World Meteorological Organization guide collection, processing, and dissemination.