These unbearably hot and humid summer months that put millions of people across the globe at risk are typically made possible by phenomena known as heat domes.
Heat domes can make already-high temperatures even more extreme and prolonged, and they are worsening in severity and becoming more frequent as the planet warms.
Here's what to know.
Heat domes are essentially high-pressure systems hovering above a region that trap heat and humidity, experts say.
They result from the northward flow of warm air. That system sends air sinking, pressure increasing and temperatures rising.
“The concept of a heat dome really means that the air in this region is so warm, and we know that warm air expands," said Jennifer Francis, a climate scientist at the Woodwell Climate Research Center. "It basically means that the layers of the atmosphere are bulging upward as well.”
Simply put, heat domes cause heat waves. They’re associated with very dry, sunny conditions that last for multiple days at a time, trap heat at the surface and help to amplify it, said Zachary Labe, climate scientist at Climate Central, an independent collective of scientists.
Heat impacted various regions of the world early in 2026.
The continental United States registered its most abnormally hot month in 132 years of records in March, with record-shattering extremes first in the Southwest and then across the rest of the nation. Heat scorched the French Open and scorched parts of India in May. Extreme heat has since been top of mind for the World Cup across the U.S., Canada and Mexico.
Starting mid-June, Europe has baked under unseasonable highs of around 40 degrees Celsius (104 Fahrenheit) in many places due to a heat dome.
Now, much of the Eastern U.S. is expected to be slammed by a long heat wave in the coming days, and already, much of the Southwest is experiencing temperatures around 100 degrees Fahrenheit (38 Celsius) this week and those temperatures could reach elsewhere by the Fourth of July holiday.
Science shows that as the planet warms — the result of humans burning coal, oil and gas — heat waves get worse, last longer and become more frequent.
“Heat waves like this are so directly connected to the climate crisis and climate change,” Francis said, "and it’s because of how we’ve been burning fossil fuels and cutting down forests for so long and increasing the concentration of heat-trapping gasses in the atmosphere.
“These kinds of heat waves and droughts and associated fires are all increasing just as we would expect them to in a warming world,” she said.
Experts say people need to stay hydrated when sweltering heat and humidity hit.
Be sure to avoid outdoor exercise in the heat of the day — and find shade, or if you can, access to air conditioning. Some cities offer resources and cooling centers to provide relief.
Cooling off in nearby pools or bodies of water can also help.
Heat domes can make it difficult to fully recover from high temperatures at night, so finding ways to stay cool during the day and evening hours are important.
“It’s those night times — especially, locations and people, who don’t have access to adequate cooling, really need to be aware of the impacts that added heat stress will have and their body’s ability not to be able to cool down," Labe said, "because humidity is going to be a really key factor in boosting those heat impacts.”
Alexa St. John is an Associated Press climate reporter. Follow her on X: @alexa_stjohn. Reach her at ast.john@ap.org.
Read more of AP’s climate coverage.
The Associated Press’ climate and environmental coverage receives financial support from multiple private foundations. AP is solely responsible for all content. Find AP’s standards for working with philanthropies, a list of supporters and funded coverage areas at AP.org.
FILE - A person uses an electric fan during a heat advisory, in the Brooklyn borough of New York, May 19, 2026. (AP Photo/Adam Gray, File)
FILE - People play in the fountains by the East River during a heat advisory, in the Brooklyn Borough of New York, May 19, 2026. (AP Photo/Adam Gray, File)
FILE - A person uses an umbrella to shield themselves from the sun during a heat advisory in Central Park, May 19, 2026, in New York. (AP Photo/Adam Gray, File)
President Donald Trump has won and lost some as the Supreme Court wraps its final week of a term focused on executive power.
The justices said Monday that Trump can fire leaders of independent agencies with one exception, ruling that central banker Lisa Cook can keep her job at the Federal Reserve for now.
The court said states can count late-arriving mailed ballots, rejecting a Trump-led challenge. It declined to consider Trump’s push to toss a $5 million jury verdict that he sexually abused writer E. Jean Carroll. And it turned away Trump defender Alan Dershowitz ’s effort to rewrite the U.S. libel law standards.
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Secretary of State Marco Rubio has met with the son of a powerful Libyan warlord as signs grow that the U.S. is intensifying efforts to broker a unity agreement between the Libya’s fractured eastern and western factions.
Rubio met on Monday with Saddam Hifter, the deputy general commander of the self-styled Libyan national army, based in the east of the country. Hifter is the son of Khalifa Hifter, widely seen as the most powerful figure in eastern and southern Libya.
The two men “discussed ongoing Libyan-led efforts to unify the country’s military, economic, and political institutions” and “possible avenues for cooperation to advance unity and peace in Libya,” the State Department said.
The U.S. is reportedly pushing an initiative under which Saddam Hifter would head a presidential council in a new unified administration that would also include Abdul Hamid Dbeibah, who runs the government in western Libya.
Monday’s meeting came after a senior official from Dbeibah’s defense ministry met with U.S. officials in Washington last week.
The U.S. president said he signed a memo to allow Americans to fix their own vehicles, saying that people had been arrested for trying to do so.
“It came to my attention because they noticed they were arresting people for fixing their car,” Trump said.
The president appeared to be referencing a diesel mechanic, Troy Lake, who violated the Clean Air Act by disabling emissions monitoring systems on trucks. Trump pardoned Lake last November.
The memo also addresses the use of aftermarket auto parts. It would supersede the ability of the California Air Resources Board to evaluate parts that affect vehicle emissions.
The top election officials in Washington and Oregon — states that conduct elections mostly by mail — commended Monday’s U.S. Supreme Court ruling allowing states to continue counting late arriving mail ballots.
Oregon allows mail ballots that are postmarked by Election Day and received in the seven days following to be counted. In Washington, mail ballots can be counted if they are postmarked by Election Day and received 21 days after a general election or 14 days after a primary.
“The decision is a win for voters, particularly for Oregon voters,” Oregon Secretary of State Tobias Read said in a phone interview.
“The ruling upholds our longstanding ballot return rules, which support accessible and fair elections,” Washington Secretary of State Steve Hobbs said in a news release.
Senate Democratic leader Chuck Schumer says the Supreme Court’s decision giving presidents free rein to fire agency heads at will gives Trump a “permission slip to turn independent federal agencies into members-only clubs for his golf buddies and cronies.”
The justices ruled in the case of former Federal Trade Commission member Rebecca Slaughter, whom Trump fired without cause despite a provision of federal law that requires a reason. The logic of the court’s decision extends to other agencies where Trump has fired board members.
Slaughter once served as Schumer’s chief counsel. Schumer says she was fired for no other reason than doing a good of a job protecting consumers.
“Instead of preserving independence intended to keep markets fair and protect consumers, Trump’s instead catering to fraudsters and monopolists. And the Supreme Court is giving him a green light to do it,” Schumer said.
California’s Secretary of State hailed Monday’s decision by the U.S. Supreme Court as a win for voters, the rule of law and democracy.
Shirley Weber, California’s first Black secretary of state, said in a statement the court “protected an important safeguard” that helps make sure voters are not disenfranchised by mail delays.
“This ruling makes one thing clear,” the Democrat said in a statement. “Our elections belong to the people, not to partisan agendas.”
Under California law, ballots received within seven days of an election are counted as long as they are postmarked by Election Day.
Anna Gomez is one of the few Democrats who have held onto their seats at federal agencies after Trump fired most of them, partly because her presence allows for a quorum that allows Chairman Brendan Carr to enact his agenda.
She warned the Supreme Court’s ruling “puts at risk how Congress intended independent agencies to function in American democracy.”
“Those who argue these agencies are unaccountable misunderstand how they were designed, as the FCC answers to Congress, the democratically elected body that created it, through oversight, appropriations, and legislation,” she said in a statement following the Court’s ruling. “When commissioners can be removed for their policy views rather than for cause, the inevitable result is an agency that pulls its punches and defers to political winds rather than the record before it.”
She said consumers “will pay the price” in higher costs, fewer choices and slower progress toward connectivity.
RNC Chairman Joe Gruters said the court’s decision upholding state practices of accepting all ballots postmarked by Election Day is a reason to pass the president’s proposed elections bill that is stalled on Capitol Hill.
“If we want fair and secure elections, Election Day should mean exactly what it says, which is why this decision makes it even more imperative that Congress pass the SAVE America Act,” Gruters said.
RNC aides distributed the statement after Trump made the same argument Monday morning. Trump’s proposal would virtually eliminate absentee voting nationally, require voters to provide citizenship documentation to register and then present certain photo identification at polling places.
Gruters said Democrats “are inviting chaos at the ballot box by allowing elections to drag on.” He did not offer any examples of such chaos, and it was the original plaintiffs who wanted the court to overturn long-established rules months before November’s elections.
Federal law enforcement is preparing for one of the capital’s largest and most complex security operations as hundreds of thousands of people visit Washington for the 250th anniversary of the nation’s freedom.
The security challenge comes amid rising political violence, including recent incidents near the White House, and a president who enjoys being at the center of public pomp yet has repeatedly faced attempts on his life.
The nation’s capital “is a target-rich environment” on a normal day, said Darren B. Cox, assistant director in charge of the FBI’s Washington Field Office. “We are prepared for any threats.”
The throngs will be joined by thousands of law enforcement officers and agents and 5,000 National Guard troops, along with military-style vehicles and other hardware not often seen on American streets.
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The president said in a social media post that it was “a Fake Case” brought against him by a woman he claims he never met.
“I will continue the fight against this Weaponization and Lawfare Case against me, including the ridiculous claim of Defamation, with all of my power and strength,” Trump wrote.
He also said the case, in which a jury found that he sexually abused the writer E. Jean Carroll in New York City in the 1990s and and later defamed her, is “really against the United States of America, and all it stands for.”
In a statement Monday, Carroll said the decision affirms the jury’s verdict will stand. “His multiple efforts to appeal that verdict have all failed and today’s ruling ends his quest to avoid accountability for his actions,” she said.
Trump said he lost his effort to remove the Federal Reserve’s Lisa Cook “on a strictly procedural basis” and would still seek to remove the central bank governor.
The court ruled 5-4 that the Federal Reserve’s Lisa Cook can remain on the Fed board as she challenges the administration’s attempts to fire her over claims of mortgage fraud, which she has denied.
Trump said in a social media post that “we will take appropriate action immediately to make sure that someone who has committed wrongdoing will not be making vital decisions concerning the Welfare of the United States of America!”
Trump called a Supreme Court ruling that ballots postmarked by Election Day can be counted days after an election a “tremendous loss.”
Trump posted on social media that the decision makes it more important for his SAVE America Act to pass. The measure would require proof of citizenship and include a ban on mail-in ballots unless that person is sick, disabled, traveling or deployed by the military, Trump noted.
“There is only one reason to oppose — CHEATING!” Trump said.
The president then called out Republican senators who have objected to the measure: Lisa Murkowski of Alaska, Susan Collins of Maine, Thom Tillis of North Carolina, Bill Cassidy of Louisiana and Mitch McConnell of Kentucky.
The firing attempt “was never about mortgage documents signed years ago” but rather “was an attempt to remove me on a manufactured pretext because I refused to bow to political pressure” from Trump, who has long sought lower interest rates from the central bank, Cook said in a written statement reacting to the court’s ruling.
Trump fired Cook last August, citing allegations that she had committed fraud in mortgage documents she signed in June and July of 2021. The Biden appointee sued to keep her job, and lower courts ruled she could remain while the case is litigated. The Supreme Court Monday upheld those rulings.
“Today’s ruling affirms a principle that has underpinned sound economic stewardship for generations: that the Federal Reserve must make all its policy decisions guided by evidence and independent judgment, free from political interference,” Cook’s statement said.
A majority of the justices ruled presidents have free rein to fire agency heads at will, despite federal laws that require a cause for such dismissals and a previous court ruling from 91 years ago.
“It is such an Honor to be the sitting President who won this Historic and Unprecedented Ruling, one of the most important ever given with respect to Presidential Powers,” Trump posted on social media.
The justices ruled in the case of former Federal Trade Commission member Rebecca Slaughter. The decision’s logic extends to National Labor Relations Board, the Merit Systems Protection Board and the Consumer Product Safety Commission.
Trump did not acknowledge that the court recognized some limits on his authorities by also ruling 5-4 that Lisa Cook can remain a central bank governor while challenging unproven mortgage fraud allegations, which she has denied.
The Supreme Court on Monday dramatically expanded presidential power, upholding Trump’s firings of the heads of independent federal agencies with one important exception, the Federal Reserve.
The justices allowed Fed governor Lisa Cook to stay in her job while she fights the Republican president’s effort to fire her over allegations of mortgage fraud, which she has denied.
But other than at the nation’s central bank, with its role of setting interest rates, the court held that presidents have free rein to fire agency heads at will, despite federal laws that require a cause for such dismissals and a 91-year-old decision that had limited executive authority. That decision, Humphrey’s Executor, was overturned.
White House press secretary Karoline Leavitt said on Monday that Steve Witkoff, who is the special envoy, and Jared Kushner, Trump’s son-in-law, are flying to Qatar to meet with the Iranians.
Leavitt said in an interview with Fox News’ “Fox & Friends” that those talks would be “high level” and that technical negotiations would occur on the sidelines. Iran has denied that the talks are happening.
Trump accused Iran of violating the ceasefire by attacking a ship last week in Strait of Hormuz, but so far the interim deal for negotiations to take place appears to have held.
The Court said states can count ballots that arrive after Election Day, a persistent target of Trump.
The decision Monday rejects a Republican-led attack on laws in more than half the states and the District of Columbia that permit mailed ballots to arrive and be counted some number of days after the election, provided they are postmarked by Election Day. The outcome spares officials the headache of changing their ballot rules just a few months before the 2026 midterm congressional elections.
In just over half those states, the more forgiving deadlines apply only to ballots cast by military and overseas voters.
Trump has claimed most mail balloting breeds fraud despite strong evidence to the contrary and years of experience. He keeps repeating that fraud caused his loss to Joe Biden in 2020 even though more than 60 court decisions and his own attorney general said that argument had no merit.
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The Supreme Court refused Monday to revive the prominent attorney’s defamation lawsuit against CNN over its coverage of remarks he made while defending Trump during his 2020 impeachment.
Justices Neil Gorsuch and Clarence Thomas dissented from the majority decision, saying legal standards for public figures who claim defamation should be reconsidered.
Alan Dershowitz said the news network aired only part of a comment he made, distorting his meaning to make him look like he’d “lost his mind,” according to court documents.
The network said that multiple outlets had interpreted his remarks in a similar way, and Dershowitz couldn’t show CNN was trying to mischaracterize what he said.
Dershowitz had urged the justices to reconsider New York Times Co. v. Sullivan, the landmark First Amendment case that made it harder for public figures to win libel lawsuits by requiring proof that an outlet either knowingly published something false, or showed a reckless disregard for the truth.
The Supreme Court said Monday it will consider a Republican push to enforce strict Arizona voting laws passed in the swing state after the 2020 election.
The high court has allowed some similar rules to take effect temporarily before, including Arizona’s proof-of-citizenship requirement for state and local elections and a Virginia purge of voter rolls that the state said was aimed at keeping noncitizens from voting.
President Donald Trump’s Republican administration joined the appeal after lower courts found the measures violated federal voting laws.
The high court is expected to hear arguments in the fall and hand down an opinion after the midterm elections.
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Trump wanted the justices to throw out a jury’s finding that he sexually abused the writer E. Jean Carroll at a New York City department store in the mid-1990s and later defamed her. The high court, in a typically brief and unexplained order, declined to take up the case.
Trump’s lawyers had argued that allegations leading to the verdict were propped up by “highly inflammatory” evidentiary rulings, including those that allowed the testimony of two other women who accused Trump of sexual abuse decades ago. Trump has denied all three women’s allegations.
Trump’s attorneys also framed the case as a distraction from Trump’s unique duties as president, though the verdict came before his return to the White House. A jury also awarded Carroll an additional $83.3 million after a second defamation trial. Trump also appealed that ruling, which is not yet before the Supreme Court.
Oil prices have inched up amid escalating tensions, with Tehran launching fresh drone and missile attacks on Bahrain and Kuwait in response to new U.S. airstrikes over the weekend.
Brent crude, the international standard, was up 58 cents to $73.18 a barrel early Monday, up from about $72 before the war. Benchmark U.S. crude gained 73 cents to $69.96 a barrel.
But there’s still plenty of risk regarding ship safety in the Strait of Hormuz following the latest attacks on vessels. ING commodities strategists Warren Patterson and Ewa Manthey said in a commentary Monday that oil traders have been “too optimistic” about the timeline for a recovery in Persian Gulf supplies.
“This complacency is odd and clearly leaves significant upside risk if the supply recovery proves slow — or if we see significant re-escalation,” the commentary said.
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Most Black Americans — 73% — say their race or ethnicity is “extremely” or “very” important to how they see themselves, according to the new AP-NORC poll. Only about half of Black adults say that being an American is highly important to their personal identity.
About half of Hispanic Americans say their race or ethnicity is highly important to them, compared to 22% of white Americans.
Vincent Harris, a 60-year-old in California who participated in the poll, says his identity as a Black man rises above other attributes for him because of how Black men are treated in America.
“A lot of people are scared of Black men just because we are Black and we are male. And that’s crazy,” Harris said. “People don’t even take you for who you are as a person; they just look at your race.”
With a social media assist from President Donald Trump, House Speaker Mike Johnson is looking this week to ease the divisions in his Republican ranks and make progress on key legislative priorities before this fall’s elections.
Johnson sent lawmakers home early last week and went to the White House after GOP tumult prevented the House from voting on two spending bills and a measure dealing with veterans’ benefits. Meanwhile, the list of legislative priorities only grew with Trump requesting another $87.6 billion, mostly to cover the war with Iran.
Johnson emerged from his White House visit with a coveted Trump social media post telling Republicans to quit voting down procedural rules that allow for final votes on their legislative priorities. “No more grandstanding, please!” Trump wrote.
Before Trump’s message, Republican and Democratic lawmakers were openly doubting whether the House would even return this week.
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FILE - E. Jean Carroll arrives at Manhattan federal court, Jan. 17, 2024, in New York. (AP Photo/Eduardo Munoz Alvarez)
President Donald Trump, from right, White House aide Natalie Harp and Interior Secretary Doug Burgum walk during a tour of the East Potomac Park golf course, Sunday, June 28, 2026, in Washington. (AP Photo/Mark Schiefelbein)
A small motorboat passes anchored vessels in the Strait of Hormuz off Bandar Abbas, Iran, Wednesday, June 17, 2026.(Amirhosein Khorgooi/ISNA via AP)
FILE - Hannah Liu, 26, of Washington, holds up a sign in support of birthright citizenship, May 15, 2025, outside of the Supreme Court in Washington. (AP Photo/Jacquelyn Martin, File)
President Donald Trump walks carrying an umbrella alongside Interior Secretary Doug Burgum, right, at East Potomac Park golf course, Sunday, June 28, 2026, in Washington. (AP Photo/Mark Schiefelbein)
FILE - A demonstrator carries an American flag upside-down near the White House during a protest taking place on the day of a military parade commemorating the Army's 250th anniversary, coinciding with President Donald Trump's 79th birthday, June 14, 2025, in Washington. (AP Photo/Alex Brandon, File)
