The Unstoppable "Blazing Chain" - The Shocking 80% Increase in Heat Streaks Hitting U.S. Cities

Prologue: Scorching Timeline
On July 25th at 7 AM, New York's X (formerly Twitter) timeline was filled with self-deprecating posts like "Nothing smells better than NYC when it’s 90 °F 😂", while simultaneously, the weather channel FOX Weather issued an alert: "EXTREME HEAT ALERT: New York City is under a major heat dome…" The central temperature of the heat dome was up to 15°F higher than usual, with a perceived temperature of 105–115°F (40–46°C). In just a few hours, the hashtag #Heatwave2025 approached 6 million mentions, and "#GlobalBoiling" entered the top 10.Newsweek

Chapter 1: What is a Heat Streak?
A heat streak refers to a period where the maximum temperature exceeds the 90th percentile of the 1991–2020 average for a city for three or more consecutive days. Climate Central's analysis of weather data from 1970–2024 revealed that in 198 out of 247 cities, or 80%, extreme heat streaks have increased, with an average addition of two occurrences per year.climatecentral.org
The most notable increases were in Nashville, Tennessee; Raleigh, North Carolina; Wheeling, West Virginia; and Wilkes-Barre, Pennsylvania, with an increase of +5 times/year compared to 50 years ago. This statistically supports the intuition that "hot days have increased."

Chapter 2: The "Chain Reaction" Caused by Heat Domes
This week, the heat dome covering North America put over 100 million people on alert. New York's heat index was expected to reach 105°F, and 115°F in the Southeast.The Guardian
When the heat index exceeds 100°F, the body's ability to cool through sweating is hindered, leading to a rapid increase in heart rate and a progression from heat cramps to heat exhaustion to heat stroke. In 2023, the U.S. Centers for Disease Control and Prevention (CDC) reported 2,325 heat-related deaths, surpassing the combined fatalities from floods, tornadoes, and lightning.The Independent

Chapter 3: The Crisis of Urban Infrastructure
Continuous high temperatures raise peak power demand, causing power lines to sag and substations to fail. During the Northeast heatwave in June 2025, Amtrak slowed trains due to track expansion, and the Washington Monument was closed in the capital.Reuters
Additionally, "corn sweat"—a phenomenon where evaporation from cornfields raises humidity—can increase the perceived temperature in the Midwest by up to +10°F.The Guardian

Chapter 4: "Perceived Temperature" Visualized on Social Media
Social media serves as another "thermometer" for heatwaves.

• Practical Type: @ClimateCentral posted an infographic stating "198 cities now average two more extreme heat streaks every year than in the 1970s," garnering 21,000 retweets in 9 hours.

• Alert Type: Weather commentator @foxweather repeatedly posted "EXTREME HEAT ALERT." The replies were filled with astonishment, such as "NYC feels hotter than Phoenix?!"Newsweek

• Self-deprecating Type: A general user's post saying "The subway is a sauna, the apartment is an oven, but the rent doesn't freeze 😫" received 15,000 likes.
  These statements share the "quality of heat" faster than official meteorological announcements and complement government cooling center information.

Chapter 5: Perspectives on Health, Gender, and Labor
Continuous high temperatures raise nighttime minimum temperatures, doubling the risk of sleep deprivation and cardiovascular issues. Outdoor workers, pregnant women, and low-income groups are particularly vulnerable. The major U.S. construction company Fluor has implemented measures such as starting work an hour earlier and distributing portable mist fans.Reuters
From a gender perspective, pregnant women have a core body temperature 0.3–0.5°C higher than when not pregnant, increasing heat stress and the risk of low birth weight.

Chapter 6: Policies and Adaptation Measures

• Urban Greening: LA's "Cool Pavement" has demonstrated a reduction in road surface temperatures by up to 5°C, prompting consideration for adoption by various cities.

• Updating Existing Infrastructure: In New York, heat-reflective paint applied to subway stations achieved an average temperature reduction of 2°C.

• Early Warning: Integration of smartphone emergency alerts with social media hashtags to reduce language/access disparities.

Epilogue: Compass for the "Global Boiling" Era
The increase in heat streaks has become a risk indicator for society as a whole, beyond just a weather topic. Social media visualizes "perception" in real-time, while researchers analyze causality with big data. The question is whether there is a will to incorporate "climate adaptation" into the standards of urban design and lifestyle. The "StayCool" trending on timelines might actually be our collective wisdom for the future.

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