Climate Matters•December 4, 2024
Record Heat Rising
KEY CONCEPTS
A new interactive tool from Climate Central can generate daily-updating graphics to visualize temperature records for 247 U.S. cities.
Most local U.S. observations align with the global trend: more daily heat records and fewer daily cold records. This growing gap between historic heat and historic cold over the past 50 years is an indicator of climate change.
Climate Central analyzed the increasing frequency of record-high temperatures compared to record-low temperatures in these cities through November 2024.
This Climate Matters analysis was made possible by open access data from NOAA/NCEI.
Climate Central created a new interactive tool that allows users to explore record high and low temperatures for 247 U.S. cities.
Generate a local graphic on the Graphics Dashboard
See a map of daily records set since 2020 in the Map Explorer
Explore data in the Data Viewer
This tool updates daily, ensuring graphics and data are accurate as records continue to be broken.
Explore daily updates for record high and low temperatures.
Local temperature extremes
To show how long-term global warming has affected local temperature extremes, Climate Central analyzed daily temperature records for each calendar day over the entire period of record at 247 U.S. locations (see Methodology). Local graphics show the percentage of hot and cold records set each decade, and from 2020-2024 (through November 26).
Most local observations follow the global trend, with daily heat records outnumbering daily cold records in recent years. Here are some highlights:
In the 2020s, 88% (217 of 247) locations set more heat records than cold records. From January 2020 through November 26, 2024, 217 of 247 locations had more record heat than record cold.
Over the same period (2020-2024), 21 locations across the U.S. only set records for heat (none for cold). Tampa had the most (setting 114 heat records and no cold records) — followed by Phoenix (110 heat records), Miami (102 heat records), San Juan (84 heat records), and Reno (68 heat records).
Heat records aren’t all about summer. As every season warms, unusually hot temperature records are being set year-round, including during colder months.
The Great Plains Dust Bowl drought of the 1930s marked a period of extraordinary heat extremes in the U.S. During the 1930’s, warm season (May-August) daily heat records outpaced daily cold records at rates not seen again until the 2010s. Data so far for the 2020s indicate that rates of record-setting heat in the current decade may exceed those seen during the 1930s.
Changing climate, changing extremes
Record-setting temperatures are part of expected variation in daily weather. But as the planet warms overall, heat extremes are expected to become more frequent and more intense.
In a stable climate, extreme highs and lows would each account for about half of all records. But since the late 1970s, daily heat records have become increasingly more common than daily cold records across the U.S. — a trend that is projected to increase with additional warming.
The observed local trends toward more record heat than cold is a hallmark of climate change as the global average temperature increases. At a national scale, daily heat records have become at least twice as frequent as daily cold records. According to NOAA, in 2024 so far (through November), the U.S. has experienced about three times more daily heat records than cold records.
LOCAL STORY ANGLES
Did climate change influence record heat today?
Climate Central’s Climate Shift Index system provides tools, data, custom maps, and local alerts to answer this question in real-time. Here are three ways to use the Climate Shift Index any day:
Use the tools. Climate Central’s Climate Shift Index map tool shows which parts of the world are experiencing high Climate Shift Index levels, every day. Explore the global Climate Shift Index map for today, tomorrow, and any day in the recent past.
Create custom maps. The Climate Shift Index is now available in KML format. Fill out this form to join our pilot project, receive the KML links, and create custom Climate Shift Index maps.
Sign up for alerts. Sign up here to receive custom email alerts when strong Climate Shift Index levels are detected in your local area.
For more local temperature rankings:
NOAA Climate at a Glance provides local temperature rankings, maps, and time series plots at national, regional, state, and city levels. NOAA’s Daily Weather Records tool provides custom reports and national summaries on daily temperature records for a range of parameters, dates, and U.S. locations.
CONTACT EXPERTS
Federico Castillo, PhD
Project Scientist and Lecturer, Department of Environmental Science, Policy, and Management
University of California - Berkeley
Expertise: climate impacts, policy, extreme weather
Contact: f.castillo@berkeley.edu
*Also available for interviews in Spanish
FIND EXPERTS
Submit a request to SciLine from the American Association for the Advancement of Science or to the Climate Data Concierge from Columbia University. These free services rapidly connect journalists to relevant scientific experts.
Browse maps of climate experts and services at regional NOAA, USDA, and Department of the Interior offices.
Explore databases such as 500 Women Scientists, BIPOC Climate and Energy Justice PhDs, and Diverse Sources to find and amplify diverse expert voices.
Reach out to your State Climate Office or the nearest Land-Grant University to connect with scientists, educators, and extension staff in your local area.
METHODOLOGY
Series of daily records (lowest minimum and highest maximum) for 247 cities, based on each calendar day, were identified over each station’s full period of record, then aggregated by decade. This series is based on daily ACIS data and represents each of the local historic records as accounted by NOAA/NCEI. Records over time may include station relocations, corresponding with the NOAA-supported data. Records for 2020-2023 and 2024 (January 1 through November 26) are included as a partial decade.