Tomorrow marks the "official" release of the newest average temperatures for Philadelphia from the good folks at NOAA and the National Weather Service. This new data incorporates the 2000's while discarding the 1970's from the mix as average temperatures are calculated on a 30 year basis locally. One of the things you will notice with average daily highs and lows is that they are smoothed out over the course of the year since the average high and low on a given day can change by a couple of degrees. The data smoothing process takes out that "jumpy" nature so the average high doesn't go from say, 80 on June 4th to 84 on June 5th back to 81 on June 6th. Drat that dreaded quality control process...just kidding!
Some of the data, specifically monthly averages, can already be used since it is based on raw data and is generally not subject to smoothing. There are a few trends, some not surprising in the grand scheme of things.
1) The average temperature in Philadelphia on an annual basis has increased by a half degree, from 55.3 to 55.8. The 1970's did feature several years of coolish temperatures (averages in the 53 or low 54 degree range) which are below the historical 1872-2010 average of 54.8. Discarding those years will naturally account for some temperature hike...as will the warm stretch in the 2000's. No single month saw their average temperature drop although December's average looks to remain steady at 37.4. All other months saw the needle move higher by at least 0.3 degrees, with February, April, and June gaining 0.9 degrees on average.
2) Winter snowfall average has increased from 20.2" to 21.8" -- the 1971-1980 time frame that's being dropped averaged 21.8" while the 00's averaged 26.8" so the increase in snows in this decade -- thank you three winters of 30"+ and December 2010 for the increase. While the late 70's were relatively snowy, the early parts of the decade were not and the snowless winter of 72-73 is no longer factored in the average snowfall...the snow starved should rejoice knowing the measuring stick of average is a full 1.6" higher.
3) Rainfall averages dropped about a half inch for the year -- winter averages trended a bit more dry while the rest of the year didn't see much major change in the rainfall department. July is still the wettest month locally, February the driest. October and November flipped spots as the 'dry' month in the Fall season.
In 2001, the average temperatures were bumped by a full degree as the 1960's were discarded. This decade's average climb was a half degree. I'll post more info this weekend about the temperature changes on a daily basis but figured I'd throw the first parcels of data out there for consumption.
