Description

Dfd: D = Continental  f = fully humid  d = very cold winter

The subarctic climate (also called subpolar climate, or boreal climate) is a climate with long, cold (often very cold) winters, and short, warm to cool summers. It is found on large landmasses, often away from the moderating effects of an ocean, generally at latitudes from 50° to 70°N, poleward of the humid continental climates. Subarctic or boreal climates are the source regions for the cold air that affects temperate latitudes to the south in winter. These climates represent Köppen climate classification Dfc, Dwc, Dsc, Dfd, Dwd and  Dsd.

In the subarctic climate Dfd, the coldest month averages below -38°C and 1–3 months average above 10 °C . There is no significant precipitation difference between seasons, but summers are wetter. There is very little precipitation. These climates occur only in eastern Siberia. In north east Asia, the Siberian anticyclone dominates in winter and temperatures as low as -50°C are not unusual. 

Köppen climate classification map for subarctic climates Dec, Dec, Dec, Dad, Dfd - source: wikicommons, author:  Alice Hunter, 2018.

Flight safety and planning considerations

In the winter months, give consideration to de-icing operations on the ground and the impact of that on turn-around times. Give consideration to the impact of extreme cold on all aspects of the operation e.g.

• exposure of personnel to the cold during walkarounds, loading and unloading,
• cold soaking of aircraft if on the ground for any length of time may cause numerous mechanical and electrical system issues such as battery function, freezing of hydraulic fluid and liquid water in galley and toilet systems, locked brakes.  

Runways may be contaminated year round. Temperature error correction will almost certainly be required to heights on approach.

Related articles

• Koppen climate classification system (KCC)