Miami Hits 100 as Brutal U.S. Heatwave Shatters Records

The U.S. heatwave gripping much of the South delivered a stunning milestone Tuesday: Miami officially reached 100 degrees Fahrenheit, tying the highest temperature ever recorded in the city and matching a record that had survived for 84 years.

Miami International Airport reached the century mark on August 18, according to local forecasters. Weather observations in Miami extend continuously back to 1895, yet only once before had the city officially touched 100 degrees — on July 21, 1942.

It was an extraordinary reading for a city where the nearby Atlantic Ocean normally acts like a giant natural air conditioner. But this time, the cooling system effectively switched off.

Why Miami suddenly hit 100 degrees

A persistent west wind pushed air toward Florida’s Atlantic coast and prevented the normal afternoon sea breeze from moving inland. Without cooler Atlantic air reaching the Miami metropolitan area, temperatures were allowed to soar through the 90s and finally reach triple digits.

The oppressive humidity made conditions even more dangerous. Across South Florida, heat-index readings — the temperature the human body actually feels when humidity is included — climbed well above 100 degrees. National Weather Service guidelines for Miami-Dade and Broward counties call for a Heat Advisory when the heat index reaches at least 105 degrees for two hours and an Excessive Heat Warning at 110 degrees.

And Miami was hardly alone. More than 72 million people across parts of the South and Southeast were under heat alerts this week, while feels-like temperatures in some locations approached 115 degrees. Triple-digit heat stretched across Texas, the Gulf Coast and parts of the Southeast.

Oklahoma City reached 109 degrees Tuesday, while Houston faced the possibility of several consecutive 100-degree days. In parts of South Texas, temperatures of 100 to 103 degrees were expected to continue into the weekend and possibly beyond.

America just recorded its hottest month ever

The latest blast of heat follows an even more remarkable national record. July 2026 was officially the hottest month ever measured across the contiguous United States since federal records began in 1895, according to the National Oceanic and Atmospheric Administration.

The nationwide average temperature reached 76.9 degrees Fahrenheit — 3.3 degrees above the 20th-century average. It narrowly surpassed the notorious heat of July 1936 and July 2012.

Every state in the Lower 48 finished July at least one degree warmer than its 20th-century average. Thirteen states ranked among their five hottest Julys ever recorded. Even more striking were the nights.

Average overnight temperatures across the country reached 64.2 degrees, making July 2026 the warmest month on record for nighttime temperatures. That matters because the human body depends on cooler nights to recover after extreme daytime heat.

The heat has not been confined to America. Globally, July 2026 tied July 2024 as the hottest July ever recorded, with global surface temperatures running 2.12 degrees Fahrenheit above the 20th-century average. The four Julys from 2023 through 2026 are now the four hottest on record worldwide.

Enter El Niño — and this one could be enormous

Another powerful force is now entering the climate equation: El Niño. NOAA officially says El Niño is strengthening rapidly in the tropical Pacific. In its latest update on August 13, the Climate Prediction Center said there is now a greater than 90 percent chance that the event becomes “very strong” during the fall and winter of 2026-27.

Even more extraordinary: NOAA currently gives a 69 percent chance that the October-through-December period produces an El Niño stronger than any event in its records dating back to 1950.

Sea-surface temperatures across parts of the eastern equatorial Pacific are already more than 2 degrees Celsius above average, while some subsurface waters have shown temperature anomalies reaching 10 degrees Celsius above normal.

El Niño occurs when unusually warm ocean water develops across the central and eastern tropical Pacific. The warming changes atmospheric circulation, rainfall patterns and jet-stream behavior around the world. It can influence drought, flooding, storms and temperatures thousands of miles away. But there is an important catch when talking about the current U.S. heatwave.

El Niño didn’t simply “cause” Miami’s record

Scientists generally cannot blame an individual hot afternoon in Miami directly on El Niño. NOAA notes that El Niño’s influence over North America is usually much weaker and less consistent during summer than during winter. Other weather patterns — including high-pressure systems, wind direction, soil moisture and local humidity — can dominate from day to day.

Miami’s 100-degree reading had an especially obvious immediate cause: west winds suppressed the cooling Atlantic sea breeze. The developing El Niño is therefore better understood as part of the larger background climate system rather than the single trigger responsible for Miami hitting 100.

Its influence may become considerably more obvious later this year. During strong El Niño winters, the Pacific jet stream often shifts south and becomes stronger, increasing storminess across parts of the southern United States while favoring warmer and drier conditions farther north.

A very strong El Niño can also temporarily boost the planet’s average temperature because an enormous amount of heat stored in the tropical Pacific Ocean is transferred into the atmosphere. That is where El Niño and climate change begin interacting.

Climate change loads the dice toward hotter extremes

El Niño is natural. Human-driven climate change is not. Earth’s climate has always experienced El Niño and La Niña cycles. What has changed is the baseline temperature upon which those natural fluctuations now operate. NOAA calculates that global temperatures have risen by roughly 2 degrees Fahrenheit since the late 19th century. The ocean has absorbed approximately 91 percent of the excess heat trapped by greenhouse gases.

That means today’s weather systems operate in a warmer atmosphere and over warmer oceans than those experienced by previous generations. Think of it like loading a pair of dice. Climate change does not dictate the exact temperature in Miami on a particular Tuesday. Weather remains variable, and records were broken long before modern global warming.

But raising the average temperature makes exceptionally hot events easier to reach and makes formerly rare extremes more common. A heat dome, stagnant high pressure or unfavorable wind pattern occurring over today’s warmer climate can therefore produce higher temperatures than an equivalent weather setup might have produced decades ago.

The broader U.S. statistics are difficult to ignore. March 2026 was already the hottest March in the 132-year U.S. record, running an extraordinary 9.4 degrees Fahrenheit above the 20th-century average. The 12-month period ending in March was also the warmest such period ever recorded across the Lower 48. Then came July — now America’s hottest month ever measured.

Miami’s ocean shield has limits

Miami’s record is particularly remarkable because geography usually protects it from temperatures seen routinely farther inland.

The Atlantic and surrounding waters keep the region humid but also moderate its daytime highs. Sea breezes normally develop as the Florida peninsula heats faster than the ocean, drawing cooler marine air toward the coast.

That is why a 100-degree temperature is so much more unusual in Miami than in cities such as Dallas, Phoenix or Las Vegas.

In more than 130 years of continuous Miami weather records, it has now happened only twice. 1942.  And now 2026.

Some relief is coming — but summer isn’t finished

Forecasters expect South Florida’s wind pattern to change later this week, allowing moisture and afternoon thunderstorms to return.

Those storms should increase cloud cover, bring desperately needed rainfall and prevent temperatures from rising quite as dramatically. But “cooler” is relative.

Heat-index values can remain dangerous even with temperatures in the low-to-mid 90s because South Florida humidity remains exceptionally high. Elsewhere across the southern United States, extreme heat is expected to persist. High pressure over Texas and surrounding states could keep temperatures near or above 100 degrees for days.

And looming over the remainder of 2026 is the rapidly strengthening Pacific. NOAA expects El Niño to continue intensifying through the end of the year and persist into the spring of 2027.

Whether it ultimately becomes the strongest El Niño in the modern record remains uncertain. But one thing is already clear: It is arriving after the United States just endured its hottest month ever recorded and as the planet continues operating at temperatures unprecedented in the modern observational era.