Much of the U.S. Midwest and the Northeast are under extreme heat conditions thanks to a heat dome that is sitting over the area. The heat dome is a high-pressure system in the upper atmosphere that causes the air below it to sink and compress and heat up. Two weeks ago it was the southwestern U.S. that was cooking under a heat wave.

Heat waves and heat domes aside, some cities are generally hot year round, and 24/7 Wall St. wanted to find out which ones are the hottest.

To determine that, we used Comparative Climatic Data from the National Oceanic and Atmospheric Administration to create an index based on four measures: Observed data — the average number of days per year with a maximum temperature of 90° F or higher; and climatological normals — normal daily maximum temperature; normal daily minimum temperature; and normal daily mean (average) temperature. The result is a list of 40 cities that are on average the hottest year round. (We only considered 244 cities with data in the 50 states.)

It is worth noting that the Comparative Climatic Data is averaging decades and decades of data points — some from early in the previous century. In today’s global warming environment, the weather in many cities is changing, with some cities becoming even hotter.

The 40 cities on the list are located in only nine states, with 25 of the cities in Texas (15) and Florida (10). Another four cities are in Louisiana, three in California, and two each in Alabama, Hawaii, and Arizona. Nevada and Mississippi have one city on the list each.

While it ranks 12th overall considering all measures in the index, Key West, Florida, has the highest average mean temperature at 78.9 degrees Fahrenheit. The city also has the highest average minimum temperature, at 74 F. (Also see: The US Cities With the Absolute Best Weather, According to Data.)

It is Phoenix, Arizona, however, that has the highest average maximum temperature, at 87.1 F, and where residents experience the most days a year where temperatures reach over 90 degrees Fahrenheit at 170 days.

Why Are We Covering This

Climate change is worsening all kinds of extreme weather globally, but much of it is related to heat — as heat fuels other types of extreme weather. Scientists’ analysis found that certain extreme heat waves last year indeed could not have been possible without climate change. Add to that the fact that extreme heat is the deadliest form of weather globally, and population exposure to extreme heat is increasing. It is interesting to see which cities are already the hottest year round, before even any heat waves or heat domes even further increasing temperatures in these places.

40. Meridian, Mississippi

• Avg. annual mean temperature: 65.9 F (#40 hottest of 244 cities)
• Avg. max temperature: 77.8 F (#37 hottest of 244 cities)
• Avg. min temperature: 54.1 F (#44 hottest of 244 cities)
• Avg. days of over 90F per year: 86 days (#30 most of 244 cities)

39. Redding, California

• Avg. annual mean temperature: 63.4 F (#57 hottest of 244 cities)
• Avg. max temperature: 76.6 F (#46 hottest of 244 cities)
• Avg. min temperature: 50.2 F (#70 hottest of 244 cities)
• Avg. days of over 90F per year: 106 days (#17 most of 244 cities)

38. Montgomery, Alabama

• Avg. annual mean temperature: 66.4 F (#37 hottest of 244 cities)
• Avg. max temperature: 78.4 F (#33 hottest of 244 cities)
• Avg. min temperature: 54.4 F (#41 hottest of 244 cities)
• Avg. days of over 90F per year: 86 days (#30 most of 244 cities)

37. Mobile, Alabama

• Avg. annual mean temperature: 67.6 F (#30 hottest of 244 cities)
• Avg. max temperature: 77.8 F (#37 hottest of 244 cities)
• Avg. min temperature: 57.4 F (#31 hottest of 244 cities)
• Avg. days of over 90F per year: 77 days (#42 most of 244 cities)

36. Wichita Falls, Texas

• Avg. annual mean temperature: 63.7 F (#54 hottest of 244 cities)
• Avg. max temperature: 76.2 F (#50 hottest of 244 cities)
• Avg. min temperature: 51.2 F (#62 hottest of 244 cities)
• Avg. days of over 90F per year: 108 days (#15 most of 244 cities)

35. Pensacola, Florida

• Avg. annual mean temperature: 69.4 F (#25 hottest of 244 cities)
• Avg. max temperature: 78.6 F (#28 hottest of 244 cities)
• Avg. min temperature: 60.3 F (#18 hottest of 244 cities)
• Avg. days of over 90F per year: 64 days (#58 most of 244 cities)

34. Shreveport, Louisiana

• Avg. annual mean temperature: 66.6 F (#35 hottest of 244 cities)
• Avg. max temperature: 77.5 F (#42 hottest of 244 cities)
• Avg. min temperature: 55.6 F (#38 hottest of 244 cities)
• Avg. days of over 90F per year: 94 days (#24 most of 244 cities)

33. Fresno, California

• Avg. annual mean temperature: 65 F (#47 hottest of 244 cities)
• Avg. max temperature: 76.3 F (#49 hottest of 244 cities)
• Avg. min temperature: 53.7 F (#48 hottest of 244 cities)
• Avg. days of over 90F per year: 109 days (#13 most of 244 cities)

32. Abilene, Texas

• Avg. annual mean temperature: 65.9 F (#40 hottest of 244 cities)
• Avg. max temperature: 78.2 F (#34 hottest of 244 cities)
• Avg. min temperature: 53.7 F (#48 hottest of 244 cities)
• Avg. days of over 90F per year: 103 days (#20 most of 244 cities)

31. Daytona Beach, Florida

• Avg. annual mean temperature: 71.5 F (#14 hottest of 244 cities)
• Avg. max temperature: 80.6 F (#16 hottest of 244 cities)
• Avg. min temperature: 62.5 F (#14 hottest of 244 cities)
• Avg. days of over 90F per year: 60 days (#61 most of 244 cities)

30. Midland-Odessa, Texas

• Avg. annual mean temperature: 65.8 F (#42 hottest of 244 cities)
• Avg. max temperature: 78.5 F (#31 hottest of 244 cities)
• Avg. min temperature: 53 F (#53 hottest of 244 cities)
• Avg. days of over 90F per year: 107 days (#16 most of 244 cities)

29. Jacksonville, Florida

• Avg. annual mean temperature: 69.3 F (#26 hottest of 244 cities)
• Avg. max temperature: 79.6 F (#24 hottest of 244 cities)
• Avg. min temperature: 58.9 F (#25 hottest of 244 cities)
• Avg. days of over 90F per year: 82 days (#36 most of 244 cities)

28. Baton Rouge, Louisiana

• Avg. annual mean temperature: 68.5 F (#27 hottest of 244 cities)
• Avg. max temperature: 78.9 F (#27 hottest of 244 cities)
• Avg. min temperature: 58 F (#29 hottest of 244 cities)
• Avg. days of over 90F per year: 90 days (#27 most of 244 cities)

27. Lake Charles, Louisiana

• Avg. annual mean temperature: 69.7 F (#23 hottest of 244 cities)
• Avg. max temperature: 79.3 F (#26 hottest of 244 cities)
• Avg. min temperature: 60.1 F (#21 hottest of 244 cities)
• Avg. days of over 90F per year: 81 days (#37 most of 244 cities)

26. El Paso, Texas

• Avg. annual mean temperature: 66.2 F (#38 hottest of 244 cities)
• Avg. max temperature: 78.6 F (#28 hottest of 244 cities)
• Avg. min temperature: 53.8 F (#46 hottest of 244 cities)
• Avg. days of over 90F per year: 109 days (#13 most of 244 cities)

25. Tallahassee, Florida

• Avg. annual mean temperature: 68.5 F (#27 hottest of 244 cities)
• Avg. max temperature: 79.7 F (#23 hottest of 244 cities)
• Avg. min temperature: 57.2 F (#33 hottest of 244 cities)
• Avg. days of over 90F per year: 92 days (#25 most of 244 cities)

24. Bakersfield, California

• Avg. annual mean temperature: 66.2 F (#38 hottest of 244 cities)
• Avg. max temperature: 78.2 F (#34 hottest of 244 cities)
• Avg. min temperature: 54.3 F (#43 hottest of 244 cities)
• Avg. days of over 90F per year: 110 days (#12 most of 244 cities)

23. New Orleans, Louisiana

• Avg. annual mean temperature: 70.5 F (#18 hottest of 244 cities)
• Avg. max temperature: 78.5 F (#31 hottest of 244 cities)
• Avg. min temperature: 62.5 F (#14 hottest of 244 cities)
• Avg. days of over 90F per year: 77 days (#42 most of 244 cities)

22. Kahului, Hawaii

• Avg. annual mean temperature: 77.1 F (#4 hottest of 244 cities)
• Avg. max temperature: 86.1 F (#2 hottest of 244 cities)
• Avg. min temperature: 68.1 F (#6 hottest of 244 cities)
• Avg. days of over 90F per year: 29 days (#123 most of 244 cities)

21. Honolulu, Hawaii

• Avg. annual mean temperature: 78 F (#2 hottest of 244 cities)
• Avg. max temperature: 84.6 F (#5 hottest of 244 cities)
• Avg. min temperature: 71.5 F (#2 hottest of 244 cities)
• Avg. days of over 90F per year: 25 days (#131 most of 244 cities)

20. Port Arthur, Texas

• Avg. annual mean temperature: 69.9 F (#22 hottest of 244 cities)
• Avg. max temperature: 79.6 F (#24 hottest of 244 cities)
• Avg. min temperature: 60.3 F (#18 hottest of 244 cities)
• Avg. days of over 90F per year: 88 days (#29 most of 244 cities)

19. Dallas, Texas

• Avg. annual mean temperature: 68 F (#29 hottest of 244 cities)
• Avg. max temperature: 77.9 F (#36 hottest of 244 cities)
• Avg. min temperature: 58.1 F (#28 hottest of 244 cities)
• Avg. days of over 90F per year: 104 days (#19 most of 244 cities)

18. Waco, Texas

• Avg. annual mean temperature: 67.1 F (#33 hottest of 244 cities)
• Avg. max temperature: 78.6 F (#28 hottest of 244 cities)
• Avg. min temperature: 55.6 F (#38 hottest of 244 cities)
• Avg. days of over 90F per year: 112 days (#11 most of 244 cities)

17. San Angelo, Texas

• Avg. annual mean temperature: 66.7 F (#34 hottest of 244 cities)
• Avg. max temperature: 80 F (#22 hottest of 244 cities)
• Avg. min temperature: 53.5 F (#51 hottest of 244 cities)
• Avg. days of over 90F per year: 115 days (#8 most of 244 cities)

16. Houston, Texas

• Avg. annual mean temperature: 70.5 F (#18 hottest of 244 cities)
• Avg. max temperature: 80.5 F (#18 hottest of 244 cities)
• Avg. min temperature: 60.5 F (#17 hottest of 244 cities)
• Avg. days of over 90F per year: 106 days (#17 most of 244 cities)

15. San Antonio, Texas

• Avg. annual mean temperature: 69.6 F (#24 hottest of 244 cities)
• Avg. max temperature: 80.3 F (#21 hottest of 244 cities)
• Avg. min temperature: 58.9 F (#25 hottest of 244 cities)
• Avg. days of over 90F per year: 117 days (#6 most of 244 cities)

14. Austin, Texas

• Avg. annual mean temperature: 70 F (#21 hottest of 244 cities)
• Avg. max temperature: 80.5 F (#18 hottest of 244 cities)
• Avg. min temperature: 59.4 F (#24 hottest of 244 cities)
• Avg. days of over 90F per year: 116 days (#7 most of 244 cities)

13. Victoria, Texas

• Avg. annual mean temperature: 70.7 F (#16 hottest of 244 cities)
• Avg. max temperature: 81.3 F (#15 hottest of 244 cities)
• Avg. min temperature: 60.2 F (#20 hottest of 244 cities)
• Avg. days of over 90F per year: 113 days (#10 most of 244 cities)

12. Key West, Florida

• Avg. annual mean temperature: 78.9 F (#1 hottest of 244 cities)
• Avg. max temperature: 83.7 F (#8 hottest of 244 cities)
• Avg. min temperature: 74 F (#1 hottest of 244 cities)
• Avg. days of over 90F per year: 50 days (#73 most of 244 cities)

11. West Palm Beach, Florida

• Avg. annual mean temperature: 75.8 F (#7 hottest of 244 cities)
• Avg. max temperature: 83 F (#11 hottest of 244 cities)
• Avg. min temperature: 68.6 F (#5 hottest of 244 cities)
• Avg. days of over 90F per year: 76 days (#44 most of 244 cities)

10. Orlando, Florida

• Avg. annual mean temperature: 73 F (#12 hottest of 244 cities)
• Avg. max temperature: 83.2 F (#9 hottest of 244 cities)
• Avg. min temperature: 62.7 F (#13 hottest of 244 cities)
• Avg. days of over 90F per year: 101 days (#22 most of 244 cities)

9. Tampa, Florida

• Avg. annual mean temperature: 74.5 F (#10 hottest of 244 cities)
• Avg. max temperature: 83 F (#11 hottest of 244 cities)
• Avg. min temperature: 66.1 F (#9 hottest of 244 cities)
• Avg. days of over 90F per year: 89 days (#28 most of 244 cities)

8. Miami, Florida

• Avg. annual mean temperature: 77.5 F (#3 hottest of 244 cities)
• Avg. max temperature: 84.2 F (#6 hottest of 244 cities)
• Avg. min temperature: 70.7 F (#4 hottest of 244 cities)
• Avg. days of over 90F per year: 72 days (#50 most of 244 cities)

7. Las Vegas, Nevada

• Avg. annual mean temperature: 70.1 F (#20 hottest of 244 cities)
• Avg. max temperature: 80.5 F (#18 hottest of 244 cities)
• Avg. min temperature: 59.6 F (#23 hottest of 244 cities)
• Avg. days of over 90F per year: 136 days (#3 most of 244 cities)

6. Corpus Christi, Texas

• Avg. annual mean temperature: 73 F (#12 hottest of 244 cities)
• Avg. max temperature: 82.3 F (#13 hottest of 244 cities)
• Avg. min temperature: 63.6 F (#12 hottest of 244 cities)
• Avg. days of over 90F per year: 114 days (#9 most of 244 cities)

5. Fort Myers, Florida

• Avg. annual mean temperature: 75.4 F (#9 hottest of 244 cities)
• Avg. max temperature: 84.9 F (#4 hottest of 244 cities)
• Avg. min temperature: 65.8 F (#10 hottest of 244 cities)
• Avg. days of over 90F per year: 102 days (#21 most of 244 cities)

4. Del Rio, Texas

• Avg. annual mean temperature: 71.5 F (#14 hottest of 244 cities)
• Avg. max temperature: 83.2 F (#9 hottest of 244 cities)
• Avg. min temperature: 59.8 F (#22 hottest of 244 cities)
• Avg. days of over 90F per year: 136 days (#3 most of 244 cities)

3. Tucson, Arizona

• Avg. annual mean temperature: 70.6 F (#17 hottest of 244 cities)
• Avg. max temperature: 84 F (#7 hottest of 244 cities)
• Avg. min temperature: 57.3 F (#32 hottest of 244 cities)
• Avg. days of over 90F per year: 148 days (#2 most of 244 cities)

2. Brownsville, Texas

• Avg. annual mean temperature: 76.2 F (#6 hottest of 244 cities)
• Avg. max temperature: 85.4 F (#3 hottest of 244 cities)
• Avg. min temperature: 67.1 F (#8 hottest of 244 cities)
• Avg. days of over 90F per year: 127 days (#5 most of 244 cities)

1. Phoenix, Arizona

• Avg. annual mean temperature: 75.6 F (#8 hottest of 244 cities)
• Avg. max temperature: 87.1 F (#1 hottest of 244 cities)
• Avg. min temperature: 64.1 F (#11 hottest of 244 cities)
• Avg. days of over 90F per year: 170 days (#1 most of 244 cities)

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