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Between June and August 2025, human-induced climate change significantly increased global temperatures, with at least 22% of the global population experiencing temperatures at Climate Shift Index (CSI) level 2 or higher every day. Nearly 955 million people faced 30 or more 'risky heat days' added by climate change, with the highest impact seen in Asia. The report also documents severe climate-driven events, including record rainfall and flooding in China, India, Pakistan, and the U.S., as well as historic wildfires in Europe and Canada.

Climate Central's analysis for June to August 2025 reveals that at least 22% of the global population experienced temperatures made at least twice as likely by climate change daily. In the U.S., over 21 million people in 32 cities faced 30 or more 'risky heat' days added by climate change, with some cities, such as Honolulu, seeing all their risky heat days attributed to human-caused warming.

August 2025 was the third warmest August globally on record, with all ten warmest Augusts occurring since 2015. In the United States, 98% of analyzed cities have experienced fall warming, and as of September 9, at least 60% of the country faces abnormally dry or drought conditions. A record-breaking marine heatwave in the North Pacific Ocean, attributed to climate change, is expected to persist into October.

August 2025 in the United States was generally cooler than normal, with an average anomaly of -0.5°F across 196 cities, though 189 of those cities have shown long-term August warming trends since 1970. Despite the monthly average, 27 cities experienced at least two weeks of Climate Shift Index (CSI) values of 2 or higher, and San Juan, Puerto Rico, saw 28 days at CSI 5, indicating a strong climate change influence on those specific days.

Climate Central argues that the Department of Energy (DOE) report, “A Critical Review of Impacts of Greenhouse Gas Emissions on the U.S. Climate,” fails to represent the scientific consensus and should not serve as a policy basis. The organization asserts that the DOE report selectively ignores two decades of scientific developments and omits major international assessments. Specifically, Climate Central contends that the DOE understates the link between human-caused climate change and the increasing intensity, rainfall, and rapid intensification of hurricanes, as well as the acceleration of sea-level rise. It further argues that the DOE's analysis of temperature extremes is misleading by focusing on the 1930s Dust Bowl era without global context and that its assessment of wildfires in the western U.S. is incomplete. Finally, the document disputes the DOE's claims regarding solar variations and the validity of extreme event attribution (EEA) methodologies, while arguing that the DOE's use of GDP to downplay disaster costs ignores the increasing physical hazards of climate change.

Wildfire smoke pollution in the U.S. has increased significantly, with per-person exposure four times higher between 2020-2024 than during 2006-2019. Research indicates that fine particulate matter (PM2.5) from wildfire smoke caused approximately 164,000 premature deaths in the U.S. from 2006 to 2020, with human-caused climate change accounting for about 15,000 of those deaths. While the West and Northwest experience the most smoke days, smoke is a nationwide issue, with every county in the contiguous U.S. seeing at least 16 smoke days annually. The rise in smoke since 2016 has stalled or reversed air quality improvements in 30 U.S. states, threatening the goals of the Clean Air Act.

Japan and South Korea experienced extreme summer heat in 2025, with Japan recording its hottest June and July in 127 years. The Climate Shift Index (CSI) indicates that human-caused climate change made these events at least five times more likely, with several cities experiencing over a month of CSI level 5 temperatures.

A forecast for extreme heat across the Southwest U.S. and northern Mexico indicates temperatures up to 18°F above normal, with the Climate Shift Index (CSI) attributing a level 5 likelihood to human-caused climate change. Approximately 53 million people are expected to be affected by these conditions, which are compounded by persistent drought in the region.

In July 2025, the United States experienced an average temperature anomaly of 1.4°F across 196 analyzed cities, with the eastern half of the country seeing above-average temperatures. The Ohio Valley was the most unusually hot region, while the West was the only region cooler than normal. Long-term data indicates that 189 of the 196 cities have seen warming trends since 1970, with Reno, Nevada, experiencing the most significant increase. Climate change influence was particularly strong in the Southeast and in San Juan, Puerto Rico, where 19 days reached a Climate Shift Index (CSI) of 5.

Severe storms in the U.S. have become significantly more costly, with billion-dollar events increasing more than five-fold between 2005–2024 compared to 1985–2004. While the overall frequency of severe and tornadic thunderstorms has not changed significantly since 1979, tornado activity is concentrating into more frequent and extreme outbreaks, and 'Tornado Alley' has shifted eastward. Projections suggest a 5-20% increase in conditions favorable to severe thunderstorms per 1.8°F of warming, with one study projecting a 6.6% increase in supercell frequency by the end of the century.

An analysis of 240 UK cities from 1970 to 2024 shows that 85% have experienced an increase in the average number of days per year exceeding 27°C. In cities such as Cambridge, Luton, and Bedford, the average number of such days rose from 1 per year in the early 1970s to 11-13 per year between 2020 and 2024, with human-caused climate change responsible for the majority of this increase.

Between 1980 and 2024, the U.S. experienced 403 billion-dollar disasters resulting in over $2.9 trillion in direct costs and nearly 17,000 deaths. The frequency and cost of these events have risen sharply, with the average time between disasters dropping from 82 days in the 1980s to 19 days in the last decade. Tropical cyclones are the costliest event type, while severe storms are the most frequent.

Analysis of 247 major U.S. cities shows that under high-emissions scenarios, summer high temperatures are projected to increase by an average of 3.6°F by 2060 and 7.9°F by 2100. For many cities, these future conditions will resemble current climates in locations hundreds of miles to the south, with 16 cities projected to reach temperatures only currently found in Pakistan, the Middle East, and North Africa.

A heat event in the Western U.S. from July 8-11, 2025, is forecast to bring temperatures 5-12°F above normal, with human-caused climate change making the event at least three to five times more likely for tens of millions of people.

Climate Central analysis finds that human-caused global warming increased the maximum wind speeds of every Atlantic hurricane in 2024 by 3 to 14 mph. This intensification was driven by record-breaking sea surface temperatures, which were made up to 800 times more likely by climate change. The report specifically highlights that major hurricanes Helene and Milton were strengthened by 10 mph and 8 mph respectively, and that three hurricanes were pushed into higher Saffir-Simpson categories due to this warming.

In June 2025, the United States experienced an average temperature anomaly of 1.5°F across 192 analyzed cities, with the Ohio Valley region showing the highest regional anomaly at 2.18°F. The analysis indicates a strong climate change influence, with 78 cities experiencing at least one week of Climate Shift Index (CSI) values of 2 or higher. Long-term data shows that 190 of 191 analyzed stations have seen positive June warming trends since 1970, with Reno, NV, experiencing the most significant increase at 7.2°F.

The document examines how the High Line's vegetation helps alleviate urban heat islands (UHIs), which are areas of elevated heat caused by population density and the built environment. It notes that while human-caused climate change warms the planet, urban infrastructure amplifies average and extreme temperatures, disproportionately affecting underserved populations. The report focuses on the role of trees and plants in urban spaces as a solution to these heat-related health and quality-of-life threats.

Climate Central's analysis of 65 major U.S. cities reveals that approximately 76% of the 6.2 million K-12 public school students in these areas attend school in 'extreme urban heat zones,' where the built environment adds at least 8°F of additional heat. The average student in these cities attends school in a neighborhood that is 8.3°F hotter due to the built environment, with the highest average additional heat found in New York City (9.6°F). The report highlights that children are particularly vulnerable to heat-related health risks, which can impair academic achievement and development, while noting that 41% of public school districts need to update or replace HVAC systems in at least half of their schools.

Climate Central analysis indicates that human-caused climate change has made the extreme heat gripping Spain and southern France in June 2025 at least five times more likely. Temperatures are forecast to reach up to 40°C, with approximately 94% of Spain's population expected to experience at least one day of exceptional climate-driven heat.

Analysis of 247 U.S. cities shows a significant increase in sweltering summer nights influenced by climate change, with average annual occurrences rising from one in the 1970s to approximately 27 currently. Nighttime temperatures have risen by an average of 3.1°F across 231 analyzed locations, with the Southwest experiencing the highest regional warming and Florida cities seeing the largest increases in climate-fueled warm nights.