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A Climate Central analysis of 239 contiguous U.S. locations from 1979 to 2022 shows that 201 locations experienced an increase in annual days with a heat index of 90°F or higher, averaging 10 additional days. The most significant increases occurred in the South, Southeast, Northwest, and Southwest, with McAllen, Texas, seeing the highest increase of 32 more days. The report emphasizes that high humidity multiplies heat risks by limiting the body's ability to cool through sweating, leading to preventable but serious illnesses like heat exhaustion and heat stroke, which disproportionately affect vulnerable populations including children, seniors, and low-income communities.

A Climate Central analysis of 241 U.S. locations shows that 195 (81%) have experienced an increase in the annual number of extremely hot days since 1970, with an average increase of 11 days. The report highlights that extreme heat is the leading cause of weather-related fatalities in the U.S. and disproportionately affects vulnerable populations, including children, the elderly, and people of color living in urban heat islands. Specific cities like Austin, Texas, and San Angelo, Texas, have seen significant increases of 47 and 39 additional extremely hot days annually, respectively.

Since 1970, average summer nighttime temperatures have increased in 95% of 241 analyzed U.S. locations, warming by an average of 3°F. These 'sweltering nights' are warming faster than daytime highs and increase heat stress, particularly for vulnerable populations and low-income households lacking air conditioning. The document highlights that the western U.S. has experienced the greatest warming, with Reno, Nevada, seeing the highest increase at 17.4°F.

The report finds that a three-day extreme heat event in Uttar Pradesh from June 14-16, 2023, was made at least two times more likely by human-caused climate change, with some areas seeing a three-fold increase in likelihood. The event resulted in at least 34 fatalities in Ballia and led to school closures in Bihar. The analysis highlights that the combination of extreme heat and high humidity increased the severity of the event, following a previous humid heat wave in April 2023 that was made over 30 times more likely by climate change.

The document describes the ocean as the planet's largest carbon sink, sequestering approximately 26% of human-released CO2 annually. It details the biological and physical carbon pumps, the role of large marine mammals and coastal ecosystems in 'blue carbon' storage, and evaluates emerging geoengineering approaches for carbon dioxide removal (CDR). The brief emphasizes that while ocean-based solutions build resilience and biodiversity, they must be paired with rapid emissions cuts to effectively slow global warming.

Analysis of 241 U.S. locations shows that 95% have experienced summer warming since 1970, with an average increase of 2.4°F. The West, Southwest, Northwest, and western Texas saw the most heating, with Reno, Nevada, recording the highest increase at 11.1°F. Additionally, 58% of analyzed locations now experience at least two more weeks of above-normal summer days than in 1970. The document highlights that excessive heat is the leading cause of weather-related deaths in the U.S. and disproportionately affects vulnerable groups, including children, the elderly, and people of color living in urban heat islands.

Climate Central's analysis of 242 U.S. locations from 1979 to 2022 shows that 71% of these sites experienced an increase in annual mosquito days, averaging a rise of 16 days. The Southeast and South currently have the highest number of mosquito days, while the Ohio Valley and Northeast saw the largest region-wide increases. The report links these trends to warming spring and fall temperatures and discusses the expanding risk of mosquito-borne diseases, such as West Nile virus and dengue, as suitable habitats shift northward and the season length for transmission increases.

Climate Central analyzed 247 U.S. locations from 1970 to 2022, finding that 232 locations experienced an increase in annual 'risky heat days'—days where temperatures exceed the local minimum mortality temperature (MMT). On average, these locations saw an increase of 21 such days per year. While increases occurred in every U.S. region, the South and Southeast were hotspots, with 91% of the 22 locations seeing the highest increases (40+ days) located there. The analysis emphasizes that extreme heat is the deadliest natural hazard in the U.S. and disproportionately affects vulnerable populations, including children, seniors, and low-income communities of color.

Urban trees in the U.S. provide critical benefits to the 80% of the population living in cities, which are otherwise prone to heat and flooding due to dense infrastructure. While an estimated 5.5 billion urban trees support city resilience, these forests require stewardship to survive the pressures of urbanization and a warming climate.

Analysis of 150 U.S. weather stations shows that 91% experienced an increase in hourly rainfall intensity between 1970 and 2022, with an average increase of 13%. This trend is linked to climate warming, which allows the atmosphere to hold more moisture, increasing the risk of flash flooding and landslides regardless of whether a location is typically wet or dry.

Since 1970, all 50 U.S. states and 241 analyzed cities have warmed, with the contiguous U.S. increasing by 2.5°F. While states reduced greenhouse gas emissions by an average of 19% between 2005 and 2020, the current pace of reduction is insufficient to meet the national target of a 50% reduction by 2030.

The document reports a significant increase in billion-dollar severe storms in the U.S., with a shift in tornado activity toward the Southeast and Mid-South. It highlights the vulnerability of mobile home residents and projects a nationwide increase in supercell frequency and a shift toward more winter and early spring storms by the end of the century.

The document analyzes how warming average annual minimum temperatures in the U.S. are shifting plant hardiness zones northward, affecting the geographic range of crops, invasive species, and pests. Based on an analysis of 242 U.S. locations from 1951 to 2022, it finds that 95% of these locations experienced warming, with some cities seeing significant zone shifts. This trend may expand the range of high-value crops but also facilitates the spread of invasive species like Kudzu and the brown marmorated stink bug.

Atmospheric rivers are corridors of moisture that provide essential water resources to the western U.S. but also cause severe flooding and landslides. Climate change is increasing the intensity and moisture content of these storms, which is projected to raise annual flood damages in the western U.S. to between $2.3 and $3.2 billion by 2090. While a series of atmospheric rivers in early 2023 significantly reduced drought coverage in California, the trend toward warmer storms is reducing snowpack and increasing the risk of compounding climate hazards.

Climate change is extending the U.S. allergy season through warming temperatures and increased CO2, which stimulate allergen production and lengthen the freeze-free growing season. These trends increase health risks, particularly for asthma sufferers, and contribute to significant economic costs. The document highlights regional variations, the role of 'thunderstorm asthma,' and the disproportionate impact on low-income and minority communities.

The Climate Central Temperature Attribution System (CC-TAS) version 2.0 utilizes ERA5 reanalysis data and CMIP6 models to estimate the influence of climate change on temperature events. It employs a skew-normal distribution to fit temperature data and uses the 'occurrence ratio' (OR) as its primary attribution metric. To ensure conservative results, the system averages estimates from median-scaling, quantile-scaling, and model-based methods, converting them into a categorical Climate Shift Index (CSI). A screening procedure is also implemented to mask regions where GFS forecast errors might confound attribution estimates.

An analysis of 215 U.S. locations reveals that 84% have experienced a long-term decrease in winter chill since 1980. This trend threatens the $27 billion U.S. non-citrus fruit and nut industry, as many temperate trees require sustained cold temperatures to ensure proper flowering, pollination, and fruit yield. The study highlights significant chill decreases in key producing regions, particularly in California, Washington, and the Southeast, affecting high-value crops such as grapes, almonds, and strawberries.

The document describes the El Niño-Southern Oscillation (ENSO) as a natural climate pattern consisting of warm (El Niño), cold (La Niña), and neutral phases driven by sea surface temperatures and pressures in the tropical Pacific. It details how these phases disrupt atmospheric circulation, affecting global precipitation and temperature. Specifically, La Niña is associated with wetter conditions in Australia and Indonesia and warmer, drier winters in the southern U.S., while El Niño is linked to drought in Australia and Indonesia and cooler, wetter winters in the southern U.S. The text emphasizes that while ENSO can nudge global temperatures, it does not mask the long-term warming trend caused by carbon pollution; for instance, 2022 remained the sixth hottest year on record despite a persistent La Niña. Historical data from the 2015-2016 El Niño event highlights severe consequences, including forest fires in Indonesia, flooding in Peru, and an estimated 60 million people impacted by extremes across Africa, Latin America, the Caribbean, and the Asia-Pacific region.

The report finds that U.S. solar and wind capacity grew to over 238 GW in 2022, generating 683,130 GWh of electricity. Texas and California emerged as the primary drivers of this growth, with Texas leading in wind capacity and generation, and California leading in solar generation. While historical growth rates might leave the U.S. short of 2030 benchmarks set by the Net-Zero America project, the report suggests that the Inflation Reduction Act of 2022 provides the necessary incentives to accelerate the transition toward the 2050 net-zero goal.

Since 1970, 204 U.S. locations have seen a decrease in annual freezing nights, with an average reduction of 13 nights. Warming has been most rapid during winter and at night, with nighttime lows warming 25% faster than daytime highs since 1900. Projections indicate that by 2040, every state in the contiguous U.S. and Alaska will experience a drop in below-freezing days under a medium-high emissions scenario, with 23 states potentially seeing three to four fewer weeks of freezing days by mid-century. While this may reduce heating costs and cold-exposure risks, it threatens snow-fed water supplies, winter recreation economies, and fruit crop yields.