US

Analysis by Dr. Fry

US Cities Summer Highs Temperature Trends - Dr. Fry’s Research

The 26 places below have a slight negative urban heat island effect trend. But the 330 below those here have a slight postive one.

330 Cities, 41 Years

Recent temperature changes and trends for 330 places scattered around the contiguous (lower 48) US. Allocation of places among regions and states is based partly on area and partly on population. So is allocation of places within each state.

Above, US summer highs in general (averaged over 122 days each year from June 1 thru September 30) have risen a lot over the past 40 years, almost all in the last 20.

In contrast, the average of daily lows in winter does not show such a trend.
The winter lows trend is up for the 1st half of the period, and down for the 2nd half.
The 42-year trend for winter daily lows was slightly upward.

This map shows the 330 places + 18 more in Alaska and Hawaii.

The map below shows the 348 weather stations used in the analysis. These are most of American stations with continuous weather records and very little missing data. Only 1 or 2 of the most populous metrolitan areas are not represented here. 10 of the metro areas feature 2 or more weather stations, such as NYC, LA, SF, Chicago, DC+, Miami+, Dallas+.

Below, 100% of states and 95% of places showed a warming trend for summer highs over the past 20 years (1995-2015). 100% of states and 92% of places showed one over the past 40 years (1975-2015).

Above, the faster warming areas, if they keep warming at their respective rates for the most recent 20 years, will have typical daily summer high temperatures before 2100 that are as hot as Las Vegas ones NOW, in various years.

64 of the places that woud get as hot as Las Vegas relatively soon are shown in the table above (also on the Home page). 51 would get that hot by 2100. Overall, 82 of the 330 (including, not shown, 10 more in Texas, 5 in California, 4 in Kansas, and 12 elsewhere) would get summers as hot as Las Vegas now by 2100 - IF 20-year trends continue.

See the US Temps data page for full data for the 330.

Above, if warming continues at the rate experienced over the past 20 years, 29 of the 49 states examined experience typical summers as hot as Las Vegas now before 2200. 8 of them become that hot by 2100, including Kansas.

Below are temperatures trends from a 2015-17 analysis, in °F per century, for the 119 places in the intermediate analysis. For the later 20 years, 1995-2015, they range from +26.9 in Hanford, California to -8.8 in Bartow, Florida. For the full 40 years, 1975-2015, they range from +20.0 in Twin Falls, Idaho to -4.6 in Bartow, Florida again.

119 places , as well as 7 in Alaska and 2 in Hawaii, are shown on the 2 maps above. The top map shows trends (°F / century) over the last 20 years, the bottom map over the last 40 years. More detail is available on the Data page.

The trends are almost identical (+5.8 and +10.5 or 10.4°F / century) for the 330 places and its subset of 119. The 330 includes most US weather stations that are largely free of missing data. New Haven CT, Stockton CA, Provo UT, Lancaster CA, Pensacola FL, and Visalia CA are the largest metro areas without a weather station included.

When will 2012 heat, the US record to date, become the new normal?

Years when 2012 (the hottest summer in US history) summer highs are expected to be the new normal, assuming warming continues at the rate for the last 20 years - in 48 states are shown on the Data page, in the States Warming Summary table.

2012 was cooler than normal in Florida, Louisiana, Washington, Oregon, Mississippi, Alabama, Georgia, South Carolina, Arizona, California, Tennessee, New England, and New Jersey. But 2012 heat could become the new normal in Nevada (2016), Virginia (2017), Texas (2018), Idaho (2019), Utah (2021), New York & Pennsylvania (2022), Kentucky (2025), Colorado & New Mexico (2026), Wyoming (2030), and Kansas (2032).

These are the summary graphs for 7 of the 8 major regions (excluding West Coast - see US Temps section), based on the 119 places.

Place and state graphs are on the US Temps Data page.

Consider other trends: Winter Highs, Summer Lows, and Winter Lows

US 26 Cities Other Temperature Trends - also Dr. Fry’s Research

Trends in daily winter highs are less pronounced in the last 22 years, but appreciably greater over the last 43 years.

While trends in summer and winter daily highs are quite pronounced, trends in daily summer lows are not. Trends in winter daily lows are not pronounced either over the 43 years. But there are strong and opposite trends in winter lows for the 1st and 2nd halves of the study period. See below.

Other Studies

Winter Is Warming Almost Everywhere in US, Most of All in Northeast 0324

Trees Stalled Effects of Global Heating in Eastern US 0224

2023-24 Articles

Phoenix Breaks Heat Record, as City Hits 110°F on 54th Day This Year 0923

Louisiana Sees ‘Unprecedented’ Wildfires amid Record Heat, Drought 0823

More than 111 Million Americans Face Extreme Heat 0823

Extreme Heat Is Covering Even More U.S. Territory than Earlier This Summer 0723

US and Europe Heat Waves ‘Virtually Impossible’ without Climate Change 0723

This Week Will Be the Summer’s Hottest So Far over the Lower 48 - 0723

Inside the Most Extreme Heat Wave the Southern U.S. Has Faced 0723

Phoenix Heat Breaks Records – Again 0723

Heat Index over 105°F Bakes US from Coast to Coast 0723

Relentless US Heat Wave Reaching Maximum Strength 0723

5 Things to Know about the Brutal U.S. Heat Wave 0723

Phoenix, Salt Lake City Set Hih Temperature Records. Where’s the Next? 0723

Record-Breaking US Heat Could Linger into August 0723

Phoenix Sets New All-Time Record with 97° Overnight Low 0723

Phoenix Breaks Record with 19th Straight Day of 110°F Highs in a Row 0723

Click for 12 more

Houston Confirms 1st Heat Death; Northern Hemisphere Boils in Severe Weather 0723

Long Heat Wave Still Chokes Southwest, as High Temperatures Move East 0723

Coast-to-Coast Heat Dome Makes Temperatures Soar, Threatens All-Time Records 0723

Millions under US Heat Warnings, as Record Temperatures to Continue 0723

Extreme Heat Is Here to Stay. Why Are We Not More Afraid? 0623

Extreme Heat Covers Areas from Texas to Mexico 0623 - most of N and NE Mexico

Texas Sets New Power Use Record as Dangerous Heat Sweeps Southern U.S. 0623

Extreme Heat is here to stay. Why are we not more afraid? 0623

Emergency Room Visits and 911 Calls for Heat Illness Spike in Texas Heat Wave 0623

Texas’s Night Temperatures Portend New, More Dangerous Kind of Heat Wave 0623

Brutal, Early Heat Wave in Texas. Climate Change Is Fueling It. 0623

Puerto Rico Is So Hot This Week, It’s Astonishing Some Meteorologists. 0623

Worcester, Massachusetts Had Its Warmest Winter in History 0323

Phoenix Just Posted the Hottest Month Ever Observed in a U.S. City 0823

The Troubling Heat in Texas and Its Ties to Climate Change 0623

Our US Winters Are Warming Faster than Our Summers 0323

100s of US Eastern Warm Records, Western Cold Records Set This Week 0223

Averaged across all 4 seasons.

2022 Articles - 24 more

Alaska’s Northernmost City Posts Warmest Winter Temperature on Record 1222

It Takes a Village to Map the Urban Heat Island Effect 1122

Summer in Worcester Mass., Was 2.4°F Hotter This Year than the 50-Year Average 0922

Dozens of Records Smashed in Midwest during Late-September Heat Wave 0922

California's Death Valley Hit 127°F, the Hottest September Day on Earth 0922

Heat Wave in US West Breaks Records, Threatens California Grid 0922

Major Heat Wave to Swell over Lower 48 after Records Fall in Northwest 0822

Record Highs Roast Northwest; Heat Wave Looms for Rest of Lower 48 - 0722

The Northern Hemisphere Is Baking, as Fires Rip through Europe 0722

Extreme Heat Prompts Alerts in 28 States, as Texas, Oklahoma Hit 115° - 0722

A Texas Meteorologist Warned of Power Outages. Then the Lights Went Out. 0722

Brutal Heat Bakes US Southeast, with More Record Highs Forecast Thursday 0622

US Heat Wave Breaks Records as More than 70 Million under Warnings 0622

US Summers Are Hotter than Ever Before 0622

US Heat Wave Brings Historically High Temperatures to Dozens of States 0522

Extreme Heat Linked to Rise in US Death Rates 0522

Europe and US Set for Scorching, Dry Summer, Scientists Say 0522

Record Heat Fueling Severe Storms, Tornadoes in Central U.S. 0522

Texas Toast - Heat Crushed Records Saturday and Will Swell Northward 0522

Record Heat to Bake California as April Snowpack Nears 70-Year Low 0422

Southern California to See Steep Hike in Fire Danger, due to Warming 0222

Super Bowl LVI in Los Angeles Could Be the Hottest on Record 0222

1/3 of Americans Already Face above-Average Warming 0222

America’s Hottest City Is Nearly Unlivable in Summer. Can Cooling Tech Save It? 0122

No September on Record in the US West Has Seen a Heat Wave like This 0922

Brutal Heat from Phoenix to Boston Triggers Alerts for 100 Million 0722

Blistering Heat Bakes the US Plains with Highs Up to 115° - 0722

2021 Articles - 26 more

Alaska Sets Record High December Temperature of 19.4°C 1221 - That’s 67°F. December in Alaska.

Death Valley Recorded Earth’s Hottest 24-Hour Average on Sunday 0721 - Overnight low was 107.7°F at Stovepipe Wells.

North America Endured Hottest June on Record 0721 - Northern Europe and Siberia also experienced an unusually hot June.

Death Valley Soars to 130°, Matching Earth’s Hottest in at Least 90 Years 0721

Nowhere Is Ready for This Heat 0621 - US Northwest records for hottest temperature ever include Portland 116°F (7° hotter than previous record), Salem 117°, Hermiston OR 118°, and Seattle 108° (5° hotter than previous record).

Records Crushed in Pacific Northwest amid Historic Heat Wave 0621 - New hottest temperature ever records were also notably higher the previous ones i in Eugene and The Dalles OR, and Olympia, Hoquiam, and Stampede Pass WA.

Click for more

Chesapeake Bay Is Warming Faster than Ocean Surface Generally 1121

Temperatures Soar as Washington & Oregon Baked by Another Major Heat Wave 0821

Californians Are Tired of Doing Their Part during Triple-Digit Heat 0721

‘Nowhere Is Safe’ - Heat Shatters Vision of Pacific Northwest as Climate Refuge 0721

American West Stuck in Cycle of ‘Heat, Drought and Fire’, Experts Warn 0721

Western US Expects More High Temperatures, as over 18 Million Face Heat Alerts 0721

No Escape from the Desperate Heat in California’s Interior 0721

As Temperatures Soared to 128°, Death Valley Smashed Heat Records in June 0721

Climate Change Drove Western Heat Wave’s Extreme Records 0721

Summer Swelter Trend - West Gets Hotter Days, East Hot Nights 0721

Pacific Northwest Heat Wave Shatters Temperature Records 0621

Pacific Northwest Faces Its Most Severe Heat Wave in History 0621

Wild High Temperatures Worldwide Show the Extent of Record June Heat Wave 0621

Record-Shattering Heat Wave Bakes Western US, Raises Drought, Fire Concerns 0621

Mega-Heat Wave Peaking in West, Breaking Records, Intensifying Drought, Fires 0621

Climate Change Batters the West Before Summer Even Begins 0621

1/8 of the US Population Is Sweltering under a Record-Breaking Heat Dome. Climate Change Is Making It Worse. 0621

It’s Been a Decade Since Houston Was This Hot, This Early On 0621

Dangerous Heat Wave Grips Southwest as Temperatures Hit 120°F in Some Areas 0621

What Do More & Earlier 90° Days, Rising Health Toll, Say about Climate Change? 0621

Western States Sizzle under Triple-Digit Temperatures 0621

Your Weather Forecast Update - Warmer Climate Will Be the New Normal 0421

Record-Breaking Temperatures to Engulf Southwest 0421

Heat and Drought Ravaged West with Last Year; Will 2021 Be Worse? 0221

Arizona’s Heat Deaths Shattered the Record Last Year 0131

U.S. West Sizzled in a November Heat Wave and Snow Drought 1221

2020 Articles - 19 more

‘Extremely Dangerous’ Fire Threat in West after Historic Weekend Heat 0920 - 121° in LA County, 120° in San Luis Obispo, 121° in Chino, 114° in Burbank, 100° in San Francisco, 122° in Palm Springs, 125° in Death Valley, downtown LA 111°. 99% of California under excessive heat warning. 121.1° in Mexicali, Mexico’s record hottest September temperature

Click for more

Average Northeast Winter Temperatures Have Warmed by up to 4.8°C since 1970 - 1120

Swing State Arizona Grapples with Deadly Heat 1120

Phoenix Has Hit 100° on Record-Breaking 1/2 (144) of the Days in 2020 - 1020

Rising Temperatures Put Heat on Nebraska's $7 Billion Corn Industry 0920

Heat ‘Rarely Ever Seen’ Is Forecast to Roast West by the Weekend 0920

Phoenix Sets 2 Monthly Heat Records in a Row, for Record Hot Summer 0920

Death Valley Soars to 130°, Potentially Earth’s Hottest since at Least 1931 - 0820

Dangerously Intense, Prolonged, and Humid Heat Wave for Most of California 0820

California Has 1st Rolling Blackouts since 2001, as Heat Wave Bakes Western US 0820

East Coast Heat Wave Peaks as 2nd Heat Dome Sets Up across the West 0720

Coast-to-Coast U.S. Heat Wave May Break Records, Hurt Crops 0720