With the receding winter and encroaching spring fighting an annual war of the worlds, March weather in the midlatitudes is notoriously volatile, characterized by wild temperature swings.

In Philadelphia, March temperature extremes range from 5 above zero to 87.

At an elevated risk of understatement, this particular March has been different: It has been astonishingly consistent, as an upper-air pattern has been locked in above the North Atlantic.

The high temperature Wednesday didn't make it past 50 — seven degrees below where it should be for a March 28 — and since March 5 the official average temperature at Philadelphia International Airport has finished below the daily normals each day.

That's 24 consecutive days of below-normal temperatures, and that's not normal — a nuanced concept, by the way not to be confused with "average." Normal values change every 30 years to keep up with local climate trends.

In fact, said Dave Dombek, a meteorologist with AccuWeather, "It's extremely rare."

A Chilly March

Tuesday marked the 26th consecutive day in which the high temperature in Philadelphia failed to reach normal levels.
Staff Graphic

Since the government began tracking how temperatures deviate from normal, over a century ago, the only March with more consecutive days with sub normal temperatures occurred in 1960 – 26, part of a 29-day streak that included the last three days of that February.

For all that, while this month will finish as the second-snowiest on record, it will not crack the top 40 for chill among the 145 Marches in the period of record.

Through Sunday, the National Weather Service Mount Holly had it ranked No. 38 with an average temperature of 38.3, or 4.3 degrees below normal, at Philadelphia International Airport.

Its ranking will slip some notches in the coming days with a run of high temperatures in the 55-60 range expected.

That would represent a significant change in daytime thermal-comfort level. The recent run has been characterized by the coolness of the days.

The maximum temperatures have averaged 6.5 degrees below normal; the nights, 2 degrees below, and for the second consecutive year, March is going to end up cooler than February.

That stubborn upper-air pattern, known as the negative phase of the North Atlantic Oscillation, is breaking down, but May will have to wait its turn.

Computer models are showing a return of cold air next week. "There's way you could see it could snow next Thursday or Thursday night," said Dombek. And, no, that wouldn't be normal.