PlainHazard

Delaware heat

Every recorded heat record since 1996 · 3 counties with a record

NOAA's Storm Events Database records 303 heat records in Delaware from 1996 through June 30, 2026, about 9.4 a year since 2000. The deadliest was the July 4, 1999 heat in New Castle County: 4 deaths and 10 injuries across 3 records. Delaware ranks 31st of 51 states and territories by count and 2nd of 50 per square mile.

Heat in Delaware, 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
3031996 to June 30, 2026
A year since 2000
9.4average
Deaths
977 injuries
Damage, 2025 dollars
–as filed
Busiest year
199838 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 Delaware?

Delaware averages about 9.4 heat records a year since 2000, 31st of 51 states and territories by count. The busiest year on record was 1998 (38). Per 10,000 square miles of land, Delaware records 1555 heat records since 1996, 2nd 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

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 Delaware have the most heat records?

Per square mile, New Castle County leads Delaware: 95 days with a heat record since 1996, 222.8 per 1,000 square miles of land. By raw count, Sussex County has the most heat records (130 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. New Castle County 222.8 (95)
  2. Kent County 133.1 (78)
  3. Sussex County 86.5 (130)

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 Delaware?

51% of its heat records since 1996 fell in June and July. The busiest month is July (96 records).

The values, month by month

Jan 20 · Feb 20 · Mar 16 · Apr 0 · May 8 · Jun 58 · Jul 96 · Aug 51 · Sep 6 · Oct 0 · Nov 12 · Dec 16 (records).

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

What were the deadliest heat records in Delaware?

Delaware: the storms with the most deaths since 1996
DateRecordCharacterKilledInjuredDamage
1999-07-04 HeatNew Castle County · forecast zone New Castle One storm episode: 3 records in 2 places; the totals are the episode's. A very strong and oppressive high pressure system that extended from the surface to aloft gave Delaware a brutal heat wave that included the entire Independence Day weekend. There were four heat related deaths, two in New Castle County, two in Sussex County. There were also about 10 heat related injuries reported. ... 4 10 –
2006-08-01 HeatKent County · forecast zone Kent One storm episode: 2 records in 2 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 dew points surged into the upper 60s and lower 70s for a time. It could have ... 2 5 –
2014-06-18 HeatSussex County · forecast zone Inland Sussex The first back-to-back days with high temperatures of 90 degrees or higher occurred across Delaware on the 17th and 18th. High temperatures were in the lower to mid 90s both days with the hottest weather on the 18th. Afternoon heat index values were in the mid 90s on the 17th and the upper 90s on the 18th. A 56-year ... 1 0 –
2013-07-15 Excessive HeatNew Castle County · forecast zone New Castle The most oppressive hot spell of the summer season affected Delaware from July 15th through the 20th. Widespread high temperatures reached into the mid 90s and the most oppressive days (combination of heat and humidity) occurred on the 18th and 19th. Morning lows those days were only around 80 degrees in highly ... 1 0 –
1998-06-25 HeatNew Castle County · forecast zone New Castle A two day hot spell brought some of the highest temperatures of the summer to the Delmarva Peninsula and ended abruptly with severe thunderstorms during the late afternoon and early evening of the 26th. The excessive heat caused the death of an 84-year-old Wilmington woman. The highest temperatures occurred on the ... 1 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.

Are heat records becoming more frequent in Delaware?

Delaware'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: Delaware and the United States by decade (2020s to June 30, 2026)
DecadeDelawareUnited StatesDelaware's share
1996-99964,3552.2%
2000s1099,1631.2%
2010s7816,4450.5%
2020-262026,7960.1%

Source: NOAA NCEI Storm Events Database.

The most recent heat records in Delaware

The 12 most recent records, to June 30, 2026
DateRecordCharacterKilledInjuredDamage
2026-06-11 Excessive HeatNew Castle County · forecast zone New Castle 0 0 –
2025-07-25 Excessive HeatNew Castle County · forecast zone New Castle 0 0 –
2025-07-25 Excessive HeatKent County · forecast zone Kent 0 0 –
2025-07-17 Excessive HeatNew Castle County · forecast zone New Castle 0 0 –
2025-07-08 Excessive HeatNew Castle County · forecast zone New Castle 0 0 –
2025-06-23 Excessive HeatNew Castle County · forecast zone New Castle 0 0 –
2025-06-23 Excessive HeatKent County · forecast zone Kent 0 0 –
2025-06-23 Excessive HeatSussex County · forecast zone Inland Sussex 0 0 –
2016-09-10 Excessive HeatNew Castle County · forecast zone New Castle 0 21 –
2016-08-20 Excessive HeatNew Castle County · forecast zone New Castle 0 3 –
2014-06-18 HeatSussex County · forecast zone Inland Sussex 1 0 –
2013-07-15 Excessive HeatNew Castle County · forecast zone New Castle 1 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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