PlainHazard

Massachusetts heat

Every recorded heat record since 1996 · 12 counties with a record

NOAA's Storm Events Database records 127 heat records in Massachusetts from 1996 through June 30, 2026, about 7.3 a year since 2000. The deadliest was the July 5, 1999 heat in Suffolk County: 2 deaths. Massachusetts ranks 40th of 51 states and territories by count and 27th of 50 per square mile.

Heat in Massachusetts, 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
1271996 to June 30, 2026
A year since 2000
7.3average
Deaths
33 injuries
Damage, 2025 dollars
–as filed
Busiest year
201021 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 Massachusetts?

Massachusetts averages about 7.3 heat records a year since 2000, 40th of 51 states and territories by count. The busiest year on record was 2010 (21). Per 10,000 square miles of land, Massachusetts records 163 heat records since 1996, 27th 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. 27. Massachusetts 163

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 Massachusetts have the most heat records?

Per square mile, Norfolk County leads Massachusetts: 24 days with a heat record since 1996, 60.6 per 1,000 square miles of land. By raw count, Berkshire County has the most heat records (42 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. Norfolk County 60.6 (25)
  2. Plymouth County 31.9 (22)
  3. Berkshire County 25.9 (42)
  4. Essex County 10.2 (6)
  5. Dukes County 9.7 (1)
  6. Worcester County 7.3 (11)
  7. Barnstable County 5.1 (2)
  8. Middlesex County 4.9 (5)
  9. Hampden County 4.9 (4)
  10. Bristol County 3.6 (5)
  11. Franklin County 2.9 (2)

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 Massachusetts?

55% of its heat records since 1996 fell in July and August. The busiest month is July (57 records).

The values, month by month

Jan 3 · Feb 4 · Mar 12 · Apr 1 · May 9 · Jun 12 · Jul 57 · Aug 13 · Sep 7 · Oct 1 · Nov 0 · Dec 8 (records).

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

What were the deadliest heat records in Massachusetts?

Massachusetts: the storms with the most deaths since 1996
DateRecordCharacterKilledInjuredDamage
1999-07-05 HeatSuffolk County · forecast zone Suffolk / Also Part Of Norfolk Bermuda high pressure brought a southwest flow of hot and humid air to Massachusetts during the holiday weekend. The temperature only fell to a low of 81 degrees at Logan International Airport in Boston on July 5th, which was a record minimum high temperature for the date. The previous record was 79 degrees which was ... 2 0 –
2013-07-05 HeatMiddlesex County · forecast zone Southeast Middlesex A 45 year old mail carrier died as a result of heat illness on July 6th. Temperatures in the area had climbed above 90 for the 3rd day in a row on the 5th, when the mail carrier was found and transported to the hospital. The high humidity levels resulted in heat indices above 90 degrees for the daylight hours and heat ... 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 Massachusetts?

Massachusetts'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: Massachusetts and the United States by decade (2020s to June 30, 2026)
DecadeMassachusettsUnited StatesMassachusetts's share
1996-99394,3550.90%
2000s139,1630.14%
2010s5216,4450.32%
2020-262326,7960.09%

Source: NOAA NCEI Storm Events Database.

The most recent heat records in Massachusetts

The 7 most recent records, to June 30, 2026
DateRecordCharacterKilledInjuredDamage
2025-06-24 HeatBerkshire County · forecast zone Southern Berkshire 0 0 –
2025-06-24 HeatBerkshire County · forecast zone Northern Berkshire 0 0 –
2025-06-23 HeatBerkshire County · forecast zone Southern Berkshire 0 0 –
2025-06-23 HeatBerkshire County · forecast zone Northern Berkshire 0 0 –
2025-06-22 Excessive HeatMiddlesex County · forecast zone Western Middlesex 0 3 –
2013-07-05 HeatMiddlesex County · forecast zone Southeast Middlesex 1 0 –
1999-07-05 HeatSuffolk County · forecast zone Suffolk / Also Part Of Norfolk 2 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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