temperaturesminimum

Temperaturesminimum, commonly written as minimum temperature or Tmin, refers to the lowest air temperature recorded at a location during a specified period, most often a calendar day. It is a standard metric in meteorology and climatology, used alongside maximum temperature and other derived indicators.

Measurements are made with a thermometer shielded from direct sun and radiant heat, typically a Stevenson screen. The Tmin is the lowest air temperature recorded during the official 24-hour period for the observing network. Time of observation and the exact period can vary by country; some networks use local midnight to local midnight, others use 00:00 to 24:00.

Common units are degrees Celsius and degrees Fahrenheit, with Kelvin used in scientific work. In climate databases Tmin is often cataloged with metadata on the time period, location, and instrument specification.

Tmin informs frost risk for crops, heating demand, energy planning, and climate analysis. It is affected by local conditions such as altitude, urban heat islands, and wind. Observational biases from instrumentation or changes in station siting require homogenization and quality control. In data-sparse regions, estimates of Tmin may be derived from satellite or gridded reanalysis products, though with larger uncertainty.

Related measures include daily maximum temperature (Tmax), mean temperature, and diurnal temperature range (Tmax − Tmin). Tmin records contribute to climate normals and long-term trend analyses, and are maintained by national meteorological services and international databases such as those maintained by the World Meteorological Organization.