MyFoxPhilly

Those of you who have been regular readers of my site know I like to talk about wild and crazy climate. Today's climate corner focuses on record temperature spreads.

March has some pretty extreme weather (except the days Philly is stuck in the 30's with an east wind and marine layer overcast) as it is a major indicator that we are about to exit one season and enter into another. The month has shown itself to feature some of the wildest temperature swings of any month and it has the second largest potential temperature swing from record monthly high to record monthly low of any month, topped only by April (thanks to an April Fools Day record low of 14 degrees). On a day to day basis, however, March provides the wildest varieties of weather on a single day going back to 1874. March 21st featured a record high of 85 degrees and a record low of just 6, a spread of 79 degrees.

There have been 33 days in Philadelphia where the record high and record low have a 70 degree or larger swing. That means that when you watch the news and you see the almanac and they show the record high and low, the difference between the two would be 70 degrees or greater. Of those, February provides the most "extreme" record spreads, with 10 days. March and January are both tied with 9 days with a spread of 70 degrees or more. April has three days with such a spread and December has two.

Why does this happen most frequently in January, February, and March? The combination of strong cold outbreaks as well as warmer air riding up the East Coast make such extremes in temperature possible. While the record highs in January and February are lower than those of March and April, the record lows are typically also lower.

March 1st is the first day where the record high in Philadelphia stays above 70 degrees consistently, a streak that lasts until December 1st. While record lows can still dip down into the single digits as late as March 21st, our earliest date where record highs are above 80 degrees is coming up on March 20th. A chart showing the record temperature spread between highs and lows is below...as you can see the gulf between the two is quite wide in the winter but narrows considerably in the summer.

Check out the list of the 33 records I brought up and a graph to show record highs and low throughout the year

Phillyweather's Blog

The Season of Extremes

Phillyweather

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