PlainHazard

Pennsylvania heat

Every recorded heat record since 1996 · 45 counties with a record

NOAA's Storm Events Database records 1,049 heat records in Pennsylvania from 1996 through June 30, 2026, about 34 a year since 2000. The deadliest was the July 4, 1999 heat: 74 deaths and 135 injuries across 7 records. Pennsylvania ranks 19th of 51 states and territories by count and 21st of 50 per square mile.

Heat in Pennsylvania, 1996 to 2026

Heat records per year (NOAA Storm Events); 2026 to June 30, 2026.

  • recorded, no damage figure
  • under $1 million
  • $1 million or more
  • $10 million or more
  • $100 million or more, or 10 deaths
  • $1 billion or more, or 100 deaths
  • a year's colour: its recorded damage or deaths
  • a year with a death
Records
1,0491996 to June 30, 2026
A year since 2000
34average
Deaths
420449 injuries
Damage, 2025 dollars
$46Kas filed
Busiest year
199890 records

Source: NOAA NCEI Storm Events Database, records through June 30, 2026; deaths and damage as filed, damage in 2025 dollars. Search the record at NCEI.

Are heat records common in Pennsylvania?

Pennsylvania averages about 34 heat records a year since 2000, 19th of 51 states and territories by count. The busiest year on record was 1998 (90). Per 10,000 square miles of land, Pennsylvania records 234 heat records since 1996, 21st of 50 states and territories by that measure.

  1. 1. New Jersey 2320
  2. 2. Delaware 1555
  3. 3. Maryland 1330
  4. 4. Oklahoma 685
  5. 5. Illinois 590
  6. 6. Mississippi 584
  7. 7. Louisiana 576
  8. 8. Missouri 547
  9. 9. Tennessee 540
  10. 10. Puerto Rico 537
  11. 21. Pennsylvania 234

Source: NOAA NCEI Storm Events Database, records since 1996, per 10,000 square miles of land area (Census Bureau 2024 Gazetteer; places under 1,000 square miles not ranked). Damage colours: Storm Events damage, 2025 dollars.

Which counties in Pennsylvania have the most heat records?

Per square mile, Philadelphia County leads Pennsylvania: 137 days with a heat record since 1996, 1019.9 per 1,000 square miles of land. By raw count, Philadelphia County has the most heat records (137 since 1996); large counties collect more records simply by covering more ground, so the ranking counts days with a record per unit of area (a storm filed for several forecast zones adds several records but one day).

  1. Philadelphia County 1019.9 (137)
  2. Delaware County 560.4 (103)
  3. Montgomery County 213.3 (117)
  4. Lehigh County 199.8 (70)
  5. Northampton County 178.5 (66)
  6. Bucks County 168.7 (114)
  7. Chester County 133.2 (112)
  8. Carbon County 91.8 (35)
  9. Berks County 81.7 (70)
  10. Monroe County 57.5 (35)
  11. Lebanon County 33.2 (12)
  12. Montour County 30.7 (4)

Source: NOAA NCEI Storm Events Database, days with a record in the county since 1996 per 1,000 square miles of land (Census Bureau 2024 Gazetteer); in brackets, the count of records.

When is the heat season in Pennsylvania?

57% of its heat records since 1996 fell in July and August. The busiest month is July (427 records).

The values, month by month

Jan 56 · Feb 50 · Mar 48 · Apr 8 · May 25 · Jun 166 · Jul 427 · Aug 171 · Sep 21 · Oct 2 · Nov 30 · Dec 45 (records).

Source: NOAA NCEI Storm Events Database, records by the month they began, since 1996.

What were the deadliest heat records in Pennsylvania?

Pennsylvania: the storms with the most deaths since 1996
DateRecordCharacterKilledInjuredDamage
1999-07-04 HeatPhiladelphia County · forecast zone Philadelphia One storm episode: 7 records in 7 places; the totals are the episode's. A very strong and oppressive high pressure system that extended from the surface to aloft gave Eastern Pennsylvania a brutal heat wave that included the entire Independence Day weekend. There were 74 heat related deaths and over 100 reported heat related injuries. High temperatures reached the 90s for the first time ... 74 135 –
2011-07-21 Excessive HeatPhiladelphia County · forecast zone Philadelphia One storm episode: 5 records in 5 places; the totals are the episode's. One of the most oppressive heat waves since mid July 1995 enveloped Eastern Pennsylvania from July 21st through the 24th. The heat was responsible for twenty-five deaths, twenty-two within Philadelphia and dozens of heat related injuries. Many locations had high temperatures that reached into the 100s. The most ... 25 60 –
1997-07-12 HeatPhiladelphia County · forecast zone Philadelphia One storm episode: 4 records in 4 places, 1997-07-12 to 1997-07-13; the totals are the episode's. The longest and hottest heat wave of the summer of 1997 brought around 6 consecutive days of high temperatures of 90 degrees or higher to Eastern Pennsylvania. Along with the oppressive heat came high humidity levels and limited rainfall. There were twenty-four heat related deaths caused by the heat wave, twenty-three ... 24 60 –
2006-08-01 HeatPhiladelphia County · forecast zone Philadelphia One storm episode: 4 records in 4 places; the totals are the episode's. A strong area of high pressure anchored over the East Coast and the western Atlantic, resulted in a stretch of excessive heat for the entire region to start off August 2006. The very hot air mass was accompanied by humid conditions as the dewpoints surged into the upper 60s and lower 70s for a time. It could have been ... 24 40 –
2008-06-07 Excessive HeatPhiladelphia County · forecast zone Philadelphia One storm episode: 7 records in 7 places; the totals are the episode's. The most oppressive heat wave of the meteorological summer affected Eastern Pennsylvania from June 7th through the 10th. There were about twenty heat related deaths, eighteen within Philadelphia. There were also a couple of drownings within rivers. The combination of high temperatures well into the 90s and dew point ... 22 33 –
2001-08-06 HeatPhiladelphia County · forecast zone Philadelphia One storm episode: 3 records in 3 places; the totals are the episode's. A ridge of high pressure both surface and aloft that was broiling the central part of the country moved east and covered Eastern Pennsylvania during the work week of August 6th. This brought a very oppressive hot spell to the region and peaked on the 9th. It was the first time since July 9th and 10th of 1993 that the ... 22 0 –
2002-07-01 HeatPhiladelphia County · forecast zone Philadelphia July started with unseasonably hot and humid weather across Eastern Pennsylvania. The hottest and most humid weather occurred on Independence Day before a cold front quietly moved through the region during the night of the 4th. Highest temperatures were well into the 90s to around 100 degrees and heat indices reached ... 15 0 –
1998-07-20 HeatPhiladelphia County · forecast zone Philadelphia One storm episode: 2 records in 2 places, 1998-07-20 to 1998-07-21; the totals are the episode's. A heat wave affected Southeast Pennsylvania from July 20th through the 23rd. Eleven persons died (Eight in Philadelphia and three in Montgomery County.) from the heat. They were usually discovered in homes with closed windows and inadequate ventilation. A 21-month-old Philadelphia baby was inadvertently left in a car ... 11 75 –
2010-07-05 Excessive HeatPhiladelphia County · forecast zone Philadelphia One storm episode: 3 records in 3 places; the totals are the episode's. The hottest weather of the summer season occurred on July 5th through the 7th throughout Eastern Pennsylvania. Except for the Poconos, many high temperatures on the 6th and 7th exceeded 100 degrees, some places even on the 5th exceeded 100 degrees. Even in the Poconos, high temperatures approached 100 degrees on the ... 10 0 –
2002-08-01 HeatMontgomery County · forecast zone Montgomery One storm episode: 3 records in 3 places; the totals are the episode's. The excessive heat that began on July 28th continued through August 5th. The combination of high temperatures in the 90s and high dew points produced heat indices of over 100 each day through the 5th. A cold frontal passage late in the day on the 5th ended the excessive heat. The hottest day of this spell for most ... 9 0 –

Source: NOAA NCEI Storm Events Database: deaths direct and indirect, as filed by the National Weather Service, summed over each storm (one episode, or one named storm filed by several offices). Storm names from the titles of FEMA declarations that name the storm's counties.

The costliest heat records in Pennsylvania

Pennsylvania: the most damaging storms since 1993, 2025 dollars
DateRecordCharacterKilledInjuredDamage
2011-06-08 Excessive HeatPhiladelphia County · forecast zone Philadelphia One storm episode: 2 records in 2 places; the totals are the episode's. 1 3 $33K

Source: NOAA NCEI Storm Events Database: property and crop damage as estimated by the National Weather Service, in 2025 dollars.

Are heat records becoming more frequent in Pennsylvania?

Pennsylvania's count per decade against the whole country's, and its share. NOAA recorded every event type only from 1996, so earlier decades are not comparable; the share of the national total is the fairer comparison across decades.

Heat: Pennsylvania and the United States by decade (2020s to June 30, 2026)
DecadePennsylvaniaUnited StatesPennsylvania's share
1996-992434,3555.6%
2000s3949,1634.3%
2010s26716,4451.6%
2020-2614526,7960.5%

Source: NOAA NCEI Storm Events Database.

The most recent heat records in Pennsylvania

The 12 most recent records, to June 30, 2026
DateRecordCharacterKilledInjuredDamage
2026-06-11 Excessive HeatDelaware County · forecast zone Delaware 0 0 –
2026-06-11 Excessive HeatPhiladelphia County · forecast zone Philadelphia 0 0 –
2025-07-30 HeatNorthumberland County · forecast zone Northumberland 0 0 –
2025-07-30 HeatSnyder County · forecast zone Snyder 0 0 –
2025-07-30 HeatJuniata County · forecast zone Juniata 0 0 –
2025-07-30 HeatPerry County · forecast zone Perry 0 0 –
2025-07-30 HeatCumberland County · forecast zone Cumberland 0 0 –
2025-07-30 HeatFranklin County · forecast zone Franklin 0 0 –
2025-07-30 HeatAdams County · forecast zone Adams 0 0 –
2025-07-30 HeatMifflin County · forecast zone Mifflin 0 0 –
2025-07-29 Excessive HeatBucks County · forecast zone Upper Bucks 0 0 –
2025-07-29 Excessive HeatPhiladelphia County · forecast zone Philadelphia 0 0 –

Source: NOAA NCEI Storm Events Database, records through June 30, 2026; the newest months are revised by NCEI as reports arrive. Search the record at NCEI.

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