In America’s Largest Cities, October Can Bring Oppressive Heat and Frigid Cold

October sits in the middle of the meteorological fall, a period when climatic conditions transition from summer to winter. According to data from nearly 3,000 weather stations from the National Oceanic and Atmospheric Administration, the average temperature nationwide falls from about 62°F on October 1st down to just 50°F by October 31st. But while temperatures reliably fall throughout the month, the prevailing trend is not always so linear–and partly because October falls directly between the end of summer and the beginning of winter, temperatures can fluctuate markedly. 

In many major U.S. cities, October temperatures have ranged from below freezing, all the way up into the triple digits. In the Dallas-Ft. Worth area, for example, the average daily temperature throughout the month is about 69°F. Still, in that same city, the mercury has plunged to as low as 31°F and climbed as high 105°F. 

Notably, such pronounced deviations from the norm are likely to become increasingly common in the era of climate change. Already in the first four days of October 2026, records for local daily temperature lows have been broken 14 times nationwide, and new daily high records have been set 338 times. 

Using data from NOAA’s Northeast Regional Climate Center, Climate Crisis 247 identified the highest and lowest October temperatures in some of America’s largest cities. We reviewed historical temperature data for 10 U.S. cities with populations of at least 900,000, and ranked those cities on the difference between highest and lowest October temperatures on record. Data on local daily temperature norms in October are also from NOAA. Supplemental population data are 5-year estimates from the U.S. Census Bureau’s 2024 American Community Survey. 

10. New York, New York

• Variation in local October temperature extremes: 66°F difference between historic high and low
• Lowest October temperature on record: 28°F on Oct. 27, 1936
• Highest October temperature on record: 94°F on Oct. 5, 1941
• Daily October temperature norms: 64.5°F daily high, 51.4°F daily low, 57.9°F daily average
• City population: 8,483,844

9. Houston, Texas

• Variation in local October temperature extremes: 70°F difference between historic high and low
• Lowest October temperature on record: 29°F on Oct. 31, 1993
• Highest October temperature on record: 99°F on Oct. 14, 2024
• Daily October temperature norms: 82.8°F daily high, 60.9°F daily low, 71.8°F daily average
• City population: 2,328,253

8. Austin, Texas

• Variation in local October temperature extremes: 70°F difference between historic high and low
• Lowest October temperature on record: 30°F on Oct. 31, 2019
• Highest October temperature on record: 100°F on Oct. 4, 2023
• Daily October temperature norms: 82.5°F daily high, 57.2°F daily low, 69.9°F daily average
• City population: 979,539

7. Philadelphia, Pennsylvania

• Variation in local October temperature extremes: 71°F difference between historic high and low
• Lowest October temperature on record: 25°F on Oct. 24, 1969
• Highest October temperature on record: 96°F on Oct. 5, 1941
• Daily October temperature norms: 67.2°F daily high, 49.2°F daily low, 58.2°F daily average
• City population: 1,579,706

6. San Antonio, Texas

• Variation in local October temperature extremes: 72°F difference between historic high and low
• Lowest October temperature on record: 27°F on Oct. 31, 1993
• Highest October temperature on record: 99°F on Oct. 12, 1991
• Daily October temperature norms: 82.2°F daily high, 60.4°F daily low, 71.3°F daily average
• City population: 1,479,835

5. Chicago, Illinois

• Variation in local October temperature extremes: 74°F difference between historic high and low
• Lowest October temperature on record: 20°F on Oct. 18, 1948
• Highest October temperature on record: 94°F on Oct. 6, 1963
• Daily October temperature norms: 63.4°F daily high, 46.5°F daily low, 54.9°F daily average
• City population: 2,711,226

4. Dallas/Fort Worth, Texas

• Variation in local October temperature extremes: 74°F difference between historic high and low
• Lowest October temperature on record: 31°F on Oct. 31, 2019
• Highest October temperature on record: 105°F on Oct. 3, 1951
• Daily October temperature norms: 79.4°F daily high, 57.8°F daily low, 68.6°F daily average
• City population: 1,307,930 / 963,194

3. San Jose, California

• Variation in local October temperature extremes: 75°F difference between historic high and low
• Lowest October temperature on record: 31°F on Oct. 22, 1906
• Highest October temperature on record: 106°F on Oct. 2, 2024
• Daily October temperature norms: 75.8°F daily high, 52.7°F daily low, 64.3°F daily average
• City population: 990,138

2. Columbus, Ohio

• Variation in local October temperature extremes: 77°F difference between historic high and low
• Lowest October temperature on record: 17°F on Oct. 21, 1952
• Highest October temperature on record: 94°F on Oct. 2, 2019
• Daily October temperature norms: 65.5°F daily high, 44.8°F daily low, 55.2°F daily average
• City population: 914,802

1. Phoenix, Arizona

• Variation in local October temperature extremes: 79°F difference between historic high and low
• Lowest October temperature on record: 34°F on Oct. 30, 1971
• Highest October temperature on record: 113°F on Oct. 6, 2024
• Daily October temperature norms: 89.2°F daily high, 65.6°F daily low, 77.4°F daily average
• City population: 1,642,323