The temperature hit zero on this date in 1994. It’s been a record 30 years since that happened.

It was the coldest day in what normally is the coldest month of the year, January.

The high was 6 degrees, and the low was 5 below zero Fahrenheit officially at Philadelphia International Airport on Jan. 19, 1994, during a season that turned salt to gold and would change the way the region’s highway departments prepare for winter.

It was the 19th time that Philly’s temperature had reached zero since Feb. 2, 1961, but Philly hasn’t seen zero since, a record 30-year stretch. The previous zero-less record was 25 years, beginning in January 1936.

The lack of zeroes almost certainly is tied to the worldwide warming, as winters around here have been trending warmer in recent decades.

Another factor probably is the site of the official thermometer — which is next to the Delaware River and near a swamp.

The effects of the siting notwithstanding, Philly has not had a winter close to that of 1993-94 since. It has had far snowier winters, but that one was singular for its cold and succession of ice storms that depleted salt supplies around here and elsewhere in the country.

The ice was melt-resistant, even when it warmed up. Jim Eberwine, who was then a National Weather Service meteorologist in Mount Holly, recalled that he didn’t see his yard “until May.”

Eberwine, who lives in Absecon, also remembered “harrowing” commutes to work.

With all that ice and snow in the populous Mid-Atlantic and Northeast after a series of relatively mild winters, salt became a precious commodity as highway departments desperately sought supplies as the winter wore on.

The highway folks learned their lesson, and since that winter PennDot and other road-maintenance departments have made it a point to overstock their salt domes.