These Counties Just Had Their Hottest Summers Ever

24/7 Wall St. Insights

• The U.S. just had its fourth warmest summer on record.
• 113 counties had their hottest summers of all time.
• While many of the hottest parts of the country set records, traditionally cool counties in the Bay Area also set records.
• Also: 2 Dividend Legends to Hold Forever

 

2024 has been another year of brutal, record-setting temperatures. The average temperature in the contiguous United States from June to August was 73.8°F, 2.5°F warmer than normal and the fourth warmest summer on record. Plagued by brutal heat domes and other intense weather events, much of the country experienced far worse extremes.

In total, 113 counties set records for average daily summer temperature in 2024, representing 11.9% of the U.S. population. Some 55 of those counties are located in the Western U.S., while 31 are in the South and 27 in the Northeast. On average, summer in the West was 3.7°F hotter than normal, while summer temperatures averaged 3.0°F above normal in the Northeast, 2.0°F above normal in the South, and 0.9°F above normal in the Midwest. Summer temperatures averaged over 5.0°F above normal in southern Nevada, Utah’s Dixie region, southeast California, and central to northwestern Arizona. 

High temperatures baked a wide swath of the United States this summer, spanning both hot, humid climate regions as well as cooler, drier parts of the country. While the four hottest counties historically – Imperial County, California, La Paz County, Arizona, Yuma County, Arizona, and Maricopa County, Arizona – all set new records for average daily temperature in summer 2024, a sweltering heat wave in the Bay Area pushed summer temperatures in Marin County, California, Monterey County, California, and Santa Clara County, California to new highs. On the other side of the country, cooler climates like Cumberland County, Maine and Sussex County, New Jersey also set records.

While a strong El Niño contributed to above-average heat, experts at NASA believe that human-made climate change was the primary driver of record-breaking heat in summer 2024. And as the effects of climate change worsen, temperatures in the United States will continue to reach new highs at an accelerating pace, with record-breaking highs registering less as statistical anomalies and more as signals of full-on climate breakdown.

To determine the counties that just had their hottest temperatures on record, 24/7 Wall St. reviewed county-level data on average monthly temperatures from the NOAA’s National Centers for Environmental Information. All counties in the contiguous U.S. were ranked based on the difference in average daily temperature in summer 2024 (June through August) from historical summer averages from 1901 to 2000. Only counties where summer 2024 ranks as the hottest summer on record – going back to 1895 – were included.

50. Monterey County, CA

• Average temperature, summer 2024: 71.1°F (+4.1°F above normal)
• Average maximum, summer 2024: 87.9°F (+4.0°F above normal)
• Average minimum, summer 2024: 54.2°F (+4.2°F above normal)
• Prior record: summer 2017 (72.5°F)
• County seat: Salinas

49. Aroostook County, ME

• Average temperature, summer 2024: 65.7°F (+4.1°F above normal)
• Average maximum, summer 2024: 76.9°F (+3.5°F above normal)
• Average minimum, summer 2024: 54.4°F (+4.6°F above normal)
• Prior record: summer 1937 (67.6°F)
• County seat: Houlton

48. Androscoggin County, ME

• Average temperature, summer 2024: 69.1°F (+4.1°F above normal)
• Average maximum, summer 2024: 79.3°F (+2.8°F above normal)
• Average minimum, summer 2024: 58.9°F (+5.4°F above normal)
• Prior record: summer 2022 (71.0°F)
• County seat: Auburn

47. Greenlee County, AZ

• Average temperature, summer 2024: 76.6°F (+4.1°F above normal)
• Average maximum, summer 2024: 90.8°F (+4.6°F above normal)
• Average minimum, summer 2024: 62.4°F (+3.7°F above normal)
• Prior record: summer 2019 (76.3°F)
• County seat: Clifton

46. Solano County, CA

• Average temperature, summer 2024: 75.4°F (+4.2°F above normal)
• Average maximum, summer 2024: 92.0°F (+5.0°F above normal)
• Average minimum, summer 2024: 58.9°F (+3.4°F above normal)
• Prior record: summer 2023 (75.9°F)
• County seat: Fairfield

45. Sagadahoc County, ME

• Average temperature, summer 2024: 69.1°F (+4.2°F above normal)
• Average maximum, summer 2024: 78.3°F (+2.9°F above normal)
• Average minimum, summer 2024: 59.8°F (+5.6°F above normal)
• Prior record: summer 1937 (71.3°F)
• County seat: Bath

44. Graham County, AZ

• Average temperature, summer 2024: 81.6°F (+4.3°F above normal)
• Average maximum, summer 2024: 95.4°F (+4.4°F above normal)
• Average minimum, summer 2024: 67.8°F (+4.2°F above normal)
• Prior record: summer 2011 (81.3°F)
• County seat: Safford

43. Lamoille County, VT

• Average temperature, summer 2024: 66.9°F (+4.3°F above normal)
• Average maximum, summer 2024: 76.5°F (+2.9°F above normal)
• Average minimum, summer 2024: 57.3°F (+5.6°F above normal)
• Prior record: summer 1937 (68.7°F)
• County seat: Hyde Park

42. Pima County, AZ

• Average temperature, summer 2024: 87.3°F (+4.3°F above normal)
• Average maximum, summer 2024: 102.1°F (+4.7°F above normal)
• Average minimum, summer 2024: 72.6°F (+4.0°F above normal)
• Prior record: summer 2011 (87.8°F)
• County seat: Tucson

41. San Juan County, UT

• Average temperature, summer 2024: 77.3°F (+4.5°F above normal)
• Average maximum, summer 2024: 91.5°F (+4.3°F above normal)
• Average minimum, summer 2024: 62.9°F (+4.7°F above normal)
• Prior record: summer 2000 (77.7°F)
• County seat: Monticello

40. Sierra County, NM

• Average temperature, summer 2024: 78.4°F (+4.5°F above normal)
• Average maximum, summer 2024: 92.6°F (+4.5°F above normal)
• Average minimum, summer 2024: 64.3°F (+4.6°F above normal)
• Prior record: summer 2024 (78.3°F)
• County seat: Truth or Consequences

39. Gila County, AZ

• Average temperature, summer 2024: 80.3°F (+4.6°F above normal)
• Average maximum, summer 2024: 95.4°F (+5.0°F above normal)
• Average minimum, summer 2024: 65.3°F (+4.1°F above normal)
• Prior record: summer 2011 (80.4°F)
• County seat: Globe

38. Luna County, NM

• Average temperature, summer 2024: 82.2°F (+4.6°F above normal)
• Average maximum, summer 2024: 96.9°F (+4.5°F above normal)
• Average minimum, summer 2024: 67.4°F (+4.6°F above normal)
• Prior record: summer 2019 (81.9°F)
• County seat: Deming

37. Pinal County, AZ

• Average temperature, summer 2024: 89.9°F (+4.7°F above normal)
• Average maximum, summer 2024: 103.5°F (+4.2°F above normal)
• Average minimum, summer 2024: 76.2°F (+5.1°F above normal)
• Prior record: summer 2011 (90.5°F)
• County seat: Florence

36. Merced County, CA

• Average temperature, summer 2024: 79.9°F (+4.7°F above normal)
• Average maximum, summer 2024: 95.6°F (+4.5°F above normal)
• Average minimum, summer 2024: 64.3°F (+4.9°F above normal)
• Prior record: summer 2020 (80.5°F)
• County seat: Merced

35. Santa Clara County, CA

• Average temperature, summer 2024: 71.9°F (+4.7°F above normal)
• Average maximum, summer 2024: 86.2°F (+5.2°F above normal)
• Average minimum, summer 2024: 57.6°F (+4.3°F above normal)
• Prior record: summer 2017 (73.1°F)
• County seat: San Jose

34. Piute County, UT

• Average temperature, summer 2024: 65.9°F (+4.7°F above normal)
• Average maximum, summer 2024: 80.9°F (+5.8°F above normal)
• Average minimum, summer 2024: 51.0°F (+3.6°F above normal)
• Prior record: summer 1969 (66.7°F)
• County seat: Junction

33. Alameda County, CA

• Average temperature, summer 2024: 72.4°F (+4.7°F above normal)
• Average maximum, summer 2024: 85.9°F (+5.4°F above normal)
• Average minimum, summer 2024: 58.8°F (+4.0°F above normal)
• Prior record: summer 2023 (73.2°F)
• County seat: Oakland

32. Colusa County, CA

• Average temperature, summer 2024: 80.1°F (+4.8°F above normal)
• Average maximum, summer 2024: 96.0°F (+3.5°F above normal)
• Average minimum, summer 2024: 64.1°F (+5.9°F above normal)
• Prior record: summer 1967 (81.2°F)
• County seat: Colusa

31. Garfield County, UT

• Average temperature, summer 2024: 71.9°F (+4.8°F above normal)
• Average maximum, summer 2024: 86.5°F (+5.7°F above normal)
• Average minimum, summer 2024: 57.4°F (+3.9°F above normal)
• Prior record: summer 1994 (71.9°F)
• County seat: Panguitch

30. Millard County, UT

• Average temperature, summer 2024: 76.0°F (+4.8°F above normal)
• Average maximum, summer 2024: 92.8°F (+5.9°F above normal)
• Average minimum, summer 2024: 59.3°F (+3.8°F above normal)
• Prior record: summer 2007 (76.4°F)
• County seat: Fillmore

29. Doña Ana County, NM

• Average temperature, summer 2024: 82.7°F (+4.9°F above normal)
• Average maximum, summer 2024: 96.6°F (+4.5°F above normal)
• Average minimum, summer 2024: 68.8°F (+5.2°F above normal)
• Prior record: summer 2023 (82.8°F)
• County seat: Las Cruces

28. Sutter County, CA

• Average temperature, summer 2024: 81.0°F (+4.9°F above normal)
• Average maximum, summer 2024: 98.0°F (+4.9°F above normal)
• Average minimum, summer 2024: 63.9°F (+4.8°F above normal)
• Prior record: summer 2020 (81.7°F)
• County seat: Yuba City

27. San Benito County, CA

• Average temperature, summer 2024: 74.8°F (+4.9°F above normal)
• Average maximum, summer 2024: 90.5°F (+4.9°F above normal)
• Average minimum, summer 2024: 59.1°F (+5.0°F above normal)
• Prior record: summer 2017 (76.2°F)
• County seat: Hollister

26. San Juan County, NM

• Average temperature, summer 2024: 75.7°F (+5.0°F above normal)
• Average maximum, summer 2024: 91.2°F (+4.6°F above normal)
• Average minimum, summer 2024: 60.3°F (+5.4°F above normal)
• Prior record: summer 2024 (75.2°F)
• County seat: Aztec

25. Sacramento County, CA

• Average temperature, summer 2024: 79.2°F (+5.0°F above normal)
• Average maximum, summer 2024: 96.2°F (+5.3°F above normal)
• Average minimum, summer 2024: 62.1°F (+4.7°F above normal)
• Prior record: summer 1967 (79.6°F)
• County seat: Sacramento

24. Madera County, CA

• Average temperature, summer 2024: 75.5°F (+5.0°F above normal)
• Average maximum, summer 2024: 91.0°F (+4.4°F above normal)
• Average minimum, summer 2024: 60.0°F (+5.7°F above normal)
• Prior record: summer 2020 (76.6°F)
• County seat: Madera

23. Butte County, CA

• Average temperature, summer 2024: 78.8°F (+5.1°F above normal)
• Average maximum, summer 2024: 94.4°F (+5.1°F above normal)
• Average minimum, summer 2024: 63.2°F (+5.1°F above normal)
• Prior record: summer 2022 (80.2°F)
• County seat: Oroville

22. Stanislaus County, CA

• Average temperature, summer 2024: 79.3°F (+5.1°F above normal)
• Average maximum, summer 2024: 95.1°F (+5.0°F above normal)
• Average minimum, summer 2024: 63.4°F (+5.2°F above normal)
• Prior record: summer 2017 (79.5°F)
• County seat: Modesto

21. Coconino County, AZ

• Average temperature, summer 2024: 75.7°F (+5.2°F above normal)
• Average maximum, summer 2024: 91.8°F (+5.8°F above normal)
• Average minimum, summer 2024: 59.7°F (+4.6°F above normal)
• Prior record: summer 2019 (75.4°F)
• County seat: Flagstaff

20. Kane County, UT

• Average temperature, summer 2024: 76.2°F (+5.2°F above normal)
• Average maximum, summer 2024: 91.6°F (+6.0°F above normal)
• Average minimum, summer 2024: 60.9°F (+4.3°F above normal)
• Prior record: summer 2019 (76.0°F)
• County seat: Kanab

19. Contra Costa County, CA

• Average temperature, summer 2024: 74.5°F (+5.2°F above normal)
• Average maximum, summer 2024: 89.1°F (+5.9°F above normal)
• Average minimum, summer 2024: 59.9°F (+4.5°F above normal)
• Prior record: summer 1998 (74.8°F)
• County seat: Martinez

18. San Joaquin County, CA

• Average temperature, summer 2024: 79.0°F (+5.2°F above normal)
• Average maximum, summer 2024: 95.9°F (+5.9°F above normal)
• Average minimum, summer 2024: 62.2°F (+4.5°F above normal)
• Prior record: summer 1967 (79.0°F)
• County seat: Stockton

17. Beaver County, UT

• Average temperature, summer 2024: 73.4°F (+5.2°F above normal)
• Average maximum, summer 2024: 89.7°F (+5.9°F above normal)
• Average minimum, summer 2024: 57.1°F (+4.5°F above normal)
• Prior record: summer 1969 (74.0°F)
• County seat: Beaver

16. Yavapai County, AZ

• Average temperature, summer 2024: 80.8°F (+5.3°F above normal)
• Average maximum, summer 2024: 96.5°F (+5.8°F above normal)
• Average minimum, summer 2024: 65.2°F (+4.8°F above normal)
• Prior record: summer 2011 (81.2°F)
• County seat: Prescott

15. Kern County, CA

• Average temperature, summer 2024: 82.1°F (+5.3°F above normal)
• Average maximum, summer 2024: 96.8°F (+4.6°F above normal)
• Average minimum, summer 2024: 67.5°F (+6.1°F above normal)
• Prior record: summer 2012 (83.4°F)
• County seat: Bakersfield

14. Wayne County, UT

• Average temperature, summer 2024: 76.0°F (+5.4°F above normal)
• Average maximum, summer 2024: 90.3°F (+6.2°F above normal)
• Average minimum, summer 2024: 61.6°F (+4.5°F above normal)
• Prior record: summer 1994 (75.8°F)
• County seat: Loa

13. Lincoln County, NV

• Average temperature, summer 2024: 78.5°F (+5.4°F above normal)
• Average maximum, summer 2024: 93.5°F (+5.3°F above normal)
• Average minimum, summer 2024: 63.5°F (+5.4°F above normal)
• Prior record: summer 1895 (78.5°F)
• County seat: Pioche

12. Iron County, UT

• Average temperature, summer 2024: 72.5°F (+5.4°F above normal)
• Average maximum, summer 2024: 88.7°F (+6.0°F above normal)
• Average minimum, summer 2024: 56.4°F (+4.8°F above normal)
• Prior record: summer 1969 (72.7°F)
• County seat: Parowan

11. Lincoln County, NM

• Average temperature, summer 2024: 75.8°F (+5.4°F above normal)
• Average maximum, summer 2024: 90.8°F (+5.5°F above normal)
• Average minimum, summer 2024: 60.7°F (+5.4°F above normal)
• Prior record: summer 2011 (75.8°F)
• County seat: Carrizozo

10. Mohave County, AZ

• Average temperature, summer 2024: 85.6°F (+5.5°F above normal)
• Average maximum, summer 2024: 99.4°F (+5.3°F above normal)
• Average minimum, summer 2024: 71.9°F (+5.7°F above normal)
• Prior record: summer 2011 (85.3°F)
• County seat: Kingman

9. Imperial County, CA

• Average temperature, summer 2024: 94.9°F (+5.5°F above normal)
• Average maximum, summer 2024: 108.9°F (+4.9°F above normal)
• Average minimum, summer 2024: 80.9°F (+6.1°F above normal)
• Prior record: summer 2015 (95.8°F)
• County seat: El Centro

8. Riverside County, CA

• Average temperature, summer 2024: 88.4°F (+5.6°F above normal)
• Average maximum, summer 2024: 102.1°F (+5.0°F above normal)
• Average minimum, summer 2024: 74.8°F (+6.2°F above normal)
• Prior record: summer 2022 (89.0°F)
• County seat: Riverside

7. Maricopa County, AZ

• Average temperature, summer 2024: 92.6°F (+5.7°F above normal)
• Average maximum, summer 2024: 106.6°F (+5.3°F above normal)
• Average minimum, summer 2024: 78.6°F (+6.1°F above normal)
• Prior record: summer 2011 (93.5°F)
• County seat: Phoenix

6. Washington County, UT

• Average temperature, summer 2024: 79.7°F (+5.7°F above normal)
• Average maximum, summer 2024: 93.8°F (+6.0°F above normal)
• Average minimum, summer 2024: 65.7°F (+5.5°F above normal)
• Prior record: summer 1969 (79.3°F)
• County seat: St. George

5. Amador County, CA

• Average temperature, summer 2024: 77.2°F (+5.7°F above normal)
• Average maximum, summer 2024: 92.8°F (+5.6°F above normal)
• Average minimum, summer 2024: 61.6°F (+6.0°F above normal)
• Prior record: summer 1967 (78.2°F)
• County seat: Jackson

4. San Bernardino County, CA

• Average temperature, summer 2024: 89.0°F (+5.8°F above normal)
• Average maximum, summer 2024: 102.6°F (+5.7°F above normal)
• Average minimum, summer 2024: 75.5°F (+5.9°F above normal)
• Prior record: summer 1969 (88.8°F)
• County seat: San Bernardino

3. Yuma County, AZ

• Average temperature, summer 2024: 94.0°F (+5.8°F above normal)
• Average maximum, summer 2024: 108.8°F (+6.0°F above normal)
• Average minimum, summer 2024: 79.3°F (+5.7°F above normal)
• Prior record: summer 2011 (95.2°F)
• County seat: Yuma

2. La Paz County, AZ

• Average temperature, summer 2024: 94.7°F (+5.9°F above normal)
• Average maximum, summer 2024: 108.3°F (+5.3°F above normal)
• Average minimum, summer 2024: 81.0°F (+6.4°F above normal)
• Prior record: summer 2011 (95.1°F)
• County seat: Parker

1. Clark County, NV

• Average temperature, summer 2024: 88.8°F (+6.3°F above normal)
• Average maximum, summer 2024: 101.6°F (+5.7°F above normal)
• Average minimum, summer 2024: 76.0°F (+6.8°F above normal)
• Prior record: summer 1969 (87.9°F)
• County seat: Las Vegas

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