<P> Meteorological Reckoning is the method of measuring the winter season used by meteorologists based on `` sensible weather patterns '' for record keeping purposes , so the start of meteorological winter varies with latitude . Winter is often defined by meteorologists to be the three calendar months with the lowest average temperatures . This corresponds to the months of December , January and February in the Northern Hemisphere , and June , July and August in the Southern Hemisphere . The coldest average temperatures of the season are typically experienced in January or February in the Northern Hemisphere and in June , July or August in the Southern Hemisphere . Nighttime predominates in the winter season , and in some regions winter has the highest rate of precipitation as well as prolonged dampness because of permanent snow cover or high precipitation rates coupled with low temperatures , precluding evaporation . Blizzards often develop and cause many transportation delays . Diamond dust , also known as ice needles or ice crystals , forms at temperatures approaching − 40 ° F ( − 40 ° C ) due to air with slightly higher moisture from aloft mixing with colder , surface based air . They are made of simple ice crystals that are hexagonal in shape . The Swedish meteorological institute ( SMHI ) define winter as when the daily mean temperatures go below 0 ° C ( 32 ° F ) for five consecutive days . According to the SMHI , winter in Scandinavia is more pronounced when Atlantic low -- pressure systems take more southerly and northerly routes , leaving the path open for high -- pressure systems to come in and cold temperatures to occur . As a result , the coldest January on record in 1987 was also the sunniest in Stockholm . </P>
<P> Meteorological Reckoning is the method of measuring the winter season used by meteorologists based on `` sensible weather patterns '' for record keeping purposes , so the start of meteorological winter varies with latitude . Winter is often defined by meteorologists to be the three calendar months with the lowest average temperatures . This corresponds to the months of December , January and February in the Northern Hemisphere , and June , July and August in the Southern Hemisphere . The coldest average temperatures of the season are typically experienced in January or February in the Northern Hemisphere and in June , July or August in the Southern Hemisphere . Nighttime predominates in the winter season , and in some regions winter has the highest rate of precipitation as well as prolonged dampness because of permanent snow cover or high precipitation rates coupled with low temperatures , precluding evaporation . Blizzards often develop and cause many transportation delays . Diamond dust , also known as ice needles or ice crystals , forms at temperatures approaching − 40 ° F ( − 40 ° C ) due to air with slightly higher moisture from aloft mixing with colder , surface based air . They are made of simple ice crystals that are hexagonal in shape . The Swedish meteorological institute ( SMHI ) define winter as when the daily mean temperatures go below 0 ° C ( 32 ° F ) for five consecutive days . According to the SMHI , winter in Scandinavia is more pronounced when Atlantic low -- pressure systems take more southerly and northerly routes , leaving the path open for high -- pressure systems to come in and cold temperatures to occur . As a result , the coldest January on record in 1987 was also the sunniest in Stockholm . </P>
when does winter occur in the northern hemisphere
when does winter occur in the northern hemisphere
December , January and February
December , January and February