Category Archives: Climate Change

Philadelphia’s Changing Climate

2016  has been a hot and dry summer  in Philadelphia. Here are a few charts that summarize the 1950-2016 daily temperature and precipitation data at Philadelphia International Airport (PHL).

August 2016 warmest in 1950 – 2016 period

The mean temperature in August, 2016 was 81.3 F, making it the hottest August in the 1950 – 2016 period.KPHL_8_Monthly Mean Temerature

41 Days with maximum daily temperature was 90 or more degrees. 


Very Dry Summer

It’s been a dry summer, we are 3.34 inches below median cumulative rainfall for this time of year. 2016 ranks 35th out of 45 years, only 11 years have had less rain than 2016 since 1970.KPHL_CumulativeRainfall_2016-09-01



Hot Summer in Philadelphia

It’s been a hot summer in Philadelphia so far this year. I started wondering in the global warming has anything to do with our recent spate of 90+ days.

First, lets look at the global warming situation. NASA has announced that July, 2016 is the warmest month on record (here, here). We are well on our way to the 3rd year of record breaking global temperatures.

NASA’s GISS Temperature Anomaly Trend

Is there a connection between global temperature increases and our 90+ summer? To find out, I first downloaded temperature data from the Weather Underground for Philadelphia’s NE Airport. I then plotted the daily maximum and minimum temperatures for the summer months of May through yesterday.

On first glance at the chart, I was sure that I found proof that our 33 90+ days was proof that global warming has hit Philadelphia. As I dug deeper I found that the number of 90+ days varies from a low of 6 in 1978,  to 41 in 2010 and a high of 43 in 1988. We are in the high end of the  6 – 43 day ranges of 90+ temperatures  range of the number of 90+ days we have had in the 1975 – 2015 period.

We need to dig deeper to find links between the number of Philadelphia’s dog days of summer and global warming. I’ll be writing on this more in the comming months.



Looking at Texas Flood with LandSat

Houston, Texas area has seen major rainfall and flooding.  This gif animation shows LandSat images of the Brazos River on May 4, 2013 and May 28, 2016 after the recent Texas storms.  (NASA link)


Brazos River: normal and May 28, 2016 flood

Rainfall Intensity and Philadelphia Creek Trash Loads

Philadelphia is not the only metropolitan area with creek trash problems, the Anacostia River in Maryland and Washington DC also has a serious creek trash problem.

The Anacostia Watershed Society and the DC Department of the Environment have conducted a number of studies of creek trash, including a very interesting study of the Nash Run (link).

image004The project investigator, Masaya Maeda, measured the trash collected in a custom built trash trap each month between March, 2009 and September, 2010. He found an interesting relationship between the hours per month of intense rainfall (>= 0.3 inches/hr) and quantity of trash captured by the trap.

This chart summarizes the Nash Run trash data,  hours of 0.3 or more  inches per hour precipitation in each month versus the quantity of trash collected.


Take a close look at the Aug, 2010 data point, it looks like an outlier. It turns out that there was a 0.5 inches/hour, a pretty intense storm that partially explains the specific situation in that month.

As Maeda reports “.. it is observed that the rainfall intensity larger than 0.3 inches/hour may be a tipping point to carry trash pieces into a nearby stream.” (pg 5- 7)

This Anacostia Watershed Society observation may be an important factor in Philadelphia Water Department’s Green City, Clean Waters Program (GC,CW).  The GC,CW program is focused on the frequent 1 inch or less storm events. This may not be helpful in controlling trash carried to Philadelphia creeks during the high intensity storms  that may be carrying most  street litter to Philadelphia creeks.

Here is a plot of the number of hours per year between 1950 to 2013  when the rainfall rate was greater than or equal to 0.3 inches/hour at Philadelphia International Airport.


The number of hours of rain  intensity >= 0.3 inches per hour ranges from a low of 7 to a high of 49 hours per year. If we look at the trend for intensities over 1 inch per hour, there seems to be a rising trend.


PWD has not conducted this type of detailed trash load by rainfall event study so we don’t have comparable rainfall intensity – trash load data for Philadelphia. We do know that we have significant trash loads in the Tookany Tacony Creek and we can see that the frequency of very  intense rain storms ( >= 1 inch per hour) is increasing. We clearly need  a street litter – creek trash study like those conducted by the Washington DC and the Anacostia Watershed Society to understand and address Philadelphia’s creek trash problem.

Excel Chart Misrepresents CO2 – Temperature Relationship


Tacony Creek Flow – June, 2013



USGS graph: Tacony Creek above Adams Ave.

Here’s the USGS gauging station hydrograph for Tacony Creek just above Adams Ave that shows the impact of the 6/7-8 rainstorm. A total of 3.82 inches of rain was recorded at Philadelphia International Airport.

(Click image to see most recent 7 days)

To see most recent 7 days, click this link: USGS graph.

East Mt Airy Role in East Germantown’s Sept. 8, 2011 Flood