Localized Changes in Heat Wave Properties Across the United States.

Heat waves are an important type of extreme climate event and directly result in more than 130 deaths per year across the United States. Heat waves have been described by several attributes and combinations which constitute various event typologies. Attributes of heat waves from 10 cities are analyzed over the period 1950–2016 to understand how these attributes determine variability in local heat waves and how climate change affects heat waves across the United States. This study uses eight definitions to differentiate heat waves and tests for temporal trends in key properties of heat waves over the period 1950–2016. At least five harmful attributes of heat waves have increased simultaneously for Dallas, Miami, New York, Phoenix, and Portland.Miami showed the greatest change in heat wave season length, frequency, and timing over the study period. Surprisingly, the greatest mean heat wave intensities above daily thresholds were for Bismarck, ND (+8.2 °C) and Syracuse, NY (+6.5 °C). Similar results across Baltimore, MD, Colorado Springs, CO, Dallas, TX, Des Moines, IA, Miami, FL, New York, NY, Phoenix, AZ, and Portland, OR, are presented to clarify the many quantitative differences in heat wave attributes and variance in quantification approaches across climates. This work explores the nexus of quantitative description and social construction of heat waves through the lens of the various regional metrics to describe heat waves. Ultimately, this assessment will guide the development of various strategies to help communities understand and prepare for heat resilience based on local heat wave components. Plain Language Summary: Heat waves are a series of consecutive days and nights with very high temperatures. They impact human health and increase water and energy demands, particularly in the urban areas. Heat waves have different lengths, occur in various seasons, and have different ranges between daytime and nighttime temperatures. These variations create numerous types of heat waves. Although heat waves happen more frequently in hot regions, residents of cities in northern climates also experience various types of heat waves. Analysis of differences in heat wave occurrences from 1950 to 2016 in 10 cities with various climates across the United States shows how different types of heat waves are changing across the United States. We found that many descriptive characteristics are increasing in value through time. For example, heat wave duration has increased in Miami, FL. The findings of this study are intended to guide policy makers, urban managers, and first responders to better prepare for future changes in regional heat waves and mitigate negative impacts of heat waves on human health and the environment. Key Points: This study uses many different definitions for heat wave to make broad comparisonsRegional differences in heat wave components complicate uniform public health and urban management strategiesFrequency and intensity of extreme climate‐related urban heat wave events are increasing for the various climates of the United States [ABSTRACT FROM AUTHOR]