A dangerous heat wave spread eastward from the Central U.S. and impacted much of the Mid-Atlantic and Northeast states from July 21-22. Very hot afternoon temperatures near and above record levels in the upper 90s and low 100s combined with dewpoints in the upper 60s to mid 70s to create heat index values between 105 and 115 degrees. Several record high minimum temperatures were also recorded with overnight readings around 80 degrees in some areas. The most intense heat and humidity were felt across the Middle and Lower Susquehanna Valley, where poor air quality further contributed to extremely oppressive conditions. The heat wave lasted several days but peaked on July 21-22. Numerous cooling and senior centers were opened to provide relief from the dangerous heat. The heat also put significant stress on power stations and HVAC systems with localized rolling blackouts and loss of AC reported in some locations.

Excessive Heat in DAUPHIN, PENNSYLVANIA
From 21-JUL-11 11:00:00 to 22-JUL-11 19:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

Heat index values exceeded 110 degrees.

Excessive Heat in YORK, PENNSYLVANIA
From 21-JUL-11 11:00:00 to 22-JUL-11 19:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

Heat index values exceeded 110 degrees.

Excessive Heat in LANCASTER, PENNSYLVANIA
From 21-JUL-11 11:00:00 to 22-JUL-11 19:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

Heat index values exceeded 110 degrees.

Excessive Heat in LEBANON, PENNSYLVANIA
From 21-JUL-11 11:00:00 to 22-JUL-11 19:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

Heat index values exceeded 110 degrees.

Excessive Heat in FRANKLIN, PENNSYLVANIA
From 21-JUL-11 11:00:00 to 22-JUL-11 19:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

Heat index values exceeded 110 degrees.

Excessive Heat in CUMBERLAND, PENNSYLVANIA
From 21-JUL-11 11:00:00 to 22-JUL-11 19:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

Heat index values exceeded 110 degrees.

Excessive Heat in SOUTHERN CLINTON, PENNSYLVANIA
From 21-JUL-11 11:00:00 to 22-JUL-11 19:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

Heat index values exceeded 105 degrees.

Excessive Heat in ADAMS, PENNSYLVANIA
From 21-JUL-11 11:00:00 to 22-JUL-11 19:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

Heat index values exceeded 110 degrees.

Excessive Heat in PERRY, PENNSYLVANIA
From 21-JUL-11 11:00:00 to 22-JUL-11 19:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

Heat index values exceeded 110 degrees.

Excessive Heat in SCHUYLKILL, PENNSYLVANIA
From 21-JUL-11 11:00:00 to 22-JUL-11 19:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

Heat index values exceeded 110 degrees.

Excessive Heat in MIFFLIN, PENNSYLVANIA
From 21-JUL-11 11:00:00 to 22-JUL-11 19:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

Heat index values exceeded 105 degrees.

Excessive Heat in JUNIATA, PENNSYLVANIA
From 21-JUL-11 11:00:00 to 22-JUL-11 19:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

Heat index values exceeded 105 degrees.

Excessive Heat in UNION, PENNSYLVANIA
From 21-JUL-11 11:00:00 to 22-JUL-11 19:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

Heat index values exceeded 105 degrees.

Excessive Heat in SNYDER, PENNSYLVANIA
From 21-JUL-11 11:00:00 to 22-JUL-11 19:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

Heat index values exceeded 105 degrees.

Excessive Heat in MONTOUR, PENNSYLVANIA
From 21-JUL-11 11:00:00 to 22-JUL-11 19:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

Heat index values exceeded 105 degrees.

Excessive Heat in NORTHUMBERLAND, PENNSYLVANIA
From 21-JUL-11 11:00:00 to 22-JUL-11 19:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

Heat index values exceeded 105 degrees.

Excessive Heat in SOUTHERN LYCOMING, PENNSYLVANIA
From 21-JUL-11 11:00:00 to 22-JUL-11 19:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

Heat index values exceeded 105 degrees.

Excessive Heat in COLUMBIA, PENNSYLVANIA
From 21-JUL-11 11:00:00 to 22-JUL-11 19:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

Heat index values exceeded 105 degrees.