A high pressure system that moved over Pennsylvania coupled with fresh snow cover from the winter storm on the 2nd and 3rd gave the area one of its coldest winter mornings in years. This was the first of three arctic blasts in the state during the month.  While this was the coldest morning of the winter for more rural areas that are normally colder on calm wind nights, it was not the harshest.  Because the high pressure system was over the region, wind chill factors and actual air temperatures were nearly the same. This was not the case a few days later and again around the 22nd of January.
The low temperature reached 8 degrees at the Philadelphia International Airport, the coldest morning in Philadelphia since January 24, 2011.  The low temperature at the Lehigh Valley International Airport was a daily record breaking 4 degrees below zero, the coldest morning of the winter and the coldest since the same minimum temperature on January 24, 2011.  The low temperature reached 1 degree above zero in Reading (Berks County), the coldest morning since it was zero degrees on January 24, 2011.  The low temperature reached 9 degrees below zero in Mount Pocono, this tied January 22nd as the coldest morning of January and the coldest day since January 17, 2009 when the low temperature reached 14 degrees below zero.
Other low temperatures on the morning of the 4th included 9 degrees below zero in East Stroudsburg (Monroe County), 5 degrees below zero in Martins Creek (Northampton County) and Glenmoore (Chester County), 4 degrees below zero in West Chester (Chester County), 3 degrees below zero in Lehighton (Carbon County) and Boyertown (Berks County), 2 degrees below zero in Doylestown (Bucks County) and Pottstown (Montgomery County), 1 degree in Warrington (Bucks County), 2 degrees in Horsham (Montgomery County) and 4 degrees in Havertown (Delaware County).

Extreme Cold/Wind Chill in DELAWARE, PENNSYLVANIA
From 04-JAN-14 00:00:00 to 04-JAN-14 10:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Extreme Cold/Wind Chill in EASTERN CHESTER, PENNSYLVANIA
From 04-JAN-14 00:00:00 to 04-JAN-14 10:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Extreme Cold/Wind Chill in EASTERN MONTGOMERY, PENNSYLVANIA
From 04-JAN-14 00:00:00 to 04-JAN-14 10:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Extreme Cold/Wind Chill in LEHIGH, PENNSYLVANIA
From 04-JAN-14 00:00:00 to 04-JAN-14 10:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Extreme Cold/Wind Chill in WESTERN CHESTER, PENNSYLVANIA
From 04-JAN-14 00:00:00 to 04-JAN-14 10:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Extreme Cold/Wind Chill in WESTERN MONTGOMERY, PENNSYLVANIA
From 04-JAN-14 00:00:00 to 04-JAN-14 10:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Extreme Cold/Wind Chill in LOWER BUCKS, PENNSYLVANIA
From 04-JAN-14 00:00:00 to 04-JAN-14 10:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Extreme Cold/Wind Chill in MONROE, PENNSYLVANIA
From 04-JAN-14 00:00:00 to 04-JAN-14 10:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Extreme Cold/Wind Chill in NORTHAMPTON, PENNSYLVANIA
From 04-JAN-14 00:00:00 to 04-JAN-14 10:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Extreme Cold/Wind Chill in BERKS, PENNSYLVANIA
From 04-JAN-14 00:00:00 to 04-JAN-14 10:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Extreme Cold/Wind Chill in PHILADELPHIA, PENNSYLVANIA
From 04-JAN-14 00:00:00 to 04-JAN-14 10:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Extreme Cold/Wind Chill in CARBON, PENNSYLVANIA
From 04-JAN-14 00:00:00 to 04-JAN-14 10:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Extreme Cold/Wind Chill in UPPER BUCKS, PENNSYLVANIA
From 04-JAN-14 00:00:00 to 04-JAN-14 10:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS