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Warnings issued for more than 100 million across the U.S.

Temperatures will be “potentially deadly,” the National Weather Service warned in a bulletin.

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Temperature records are forecast to be broken Sunday as a dangerous heat wave threatens large swaths of the country with potentially deadly triple-digit highs.

“Take the heat seriously and avoid time outdoors,” the National Weather Service warned in a bulletin early Sunday. “Temperatures will reach levels that pose a health risk and are potentially deadly to anyone without effective cooling and/or adequate hydration. Heat is the leading weather-related killer in the U.S.”

Excessive heat warnings and advisories are in effect “from the Pacific Northwest, California, and the Great Basin to parts of the Southern Plains, Central Gulf Coast, and southern tip of Florida,” the bulletin said.

What to know

  • Phoenix had its 16th consecutive day of 110-degree or higher temperatures Saturday, putting it on track to beat the longest measured stretch of such heat. The record was 18 days, in 1974.
  • More than 110 million people, or about a third of people in the U.S., are under excessive heat warnings and advisories.
  • Firefighters are battling three separate brush fires in blistering heat and low humidity in sparsely populated, hilly areas southeast of Los Angeles.
  • Excessive rain and flash flooding are possible across the Northeast, along with the isolated threat of severe thunderstorms.

Phoenix emergency personnel stretched by heat

As Phoenix broke yet another daily record with 118 degrees yesterday, Dr. Frank LoVecchio, an emergency medicine physician with Valleywise Health, said the heat is straining local hospitals.

“This is the worst summer in recent memory," he said. "I’ve been working here since 1996, this same hospital, and this is one of the worst summers because we’ve had so many days in a row … this super warm weather.”

As of today, the city has had 17 consecutive days above 110 degrees. Walking into the Valleywise ER is to see hallways lined with patients hooked up to IV lines, drowsy from heat exhaustion.

“We’re overcrowded with patients,” LoVecchio said, adding that 20% of patients are there for something heat-related. “We’re using overflow.”

Ice pools are prepared on stretchers by medical staff members for the inevitable next patient who needs an immediate cooling-down. LoVecchio said that some patients have come in with internal temperatures of 107 and that they can sometimes be saved. The one who was rushed in with an internal temp of 110 last week could not.

The Phoenix Fire Department has been feeling the strain, too. No strangers to heat, Arizona firefighters take ice baths after particularly grueling calls.

Taking IVs in coolers filled with ice, they’ve been responding to an uptick of the same heat-related calls that bring more patients to the hospital, including a man who had third-degree burns on his body from lying on the asphalt. The firefighters believe the man was among those in the city experiencing homelessness — the most vulnerable population in the heat wave.

NWS map highlights stark differences in California temperatures

A National Weather Service map highlights just how hot it's getting in parts of California and how much those temperatures can vary.

The map shows many parts of inland California near San Francisco hitting triple digits, even getting up to 108 degrees. Temperatures closer to the water remained mild, in the 60s and 70s.

Busy weekend for Southern California firefighters

Hot temperatures jump started the wildfire season for firefighters in Southern California.

The fast-moving Rabbit fire broke out Friday afternoon near Beaumont, California. The fire spread quickly in steep terrain and thick brush, and by today it had grown to 7,600 acres.

The fire — the largest of four burning in Riverside County southeast of Los Angeles — marked the start of California’s fire season, which was spurred by the intense heat sizzling through the Southern U.S.

The fire is in rugged terrain but near neighborhoods in Beaumont, a city of about 55,000 people. Firefighters were working to build a containment line to protect neighborhoods along the northeast edge of the burned area. So far, no structures had been damaged as of Sunday afternoon. More than 800 workers were assigned to the fire, which was considered about 10% contained, according to the California Department of Forestry and Fire Protection.

One person was injured in the Rabbit fire; the circumstances of the injury were not immediately clear.  

“It was one civilian who did sustain an injury. We don’t have information on the type of injury. It was moderate. She was transported to a local hospital via ground ambulance,” said Maggie Cline De La Rosa, a fire information officer for Cal Fire.

The South Coast Air Quality Management District extended a wildfire smoke advisory into tomorrow for communities near the Rabbit fire, including Beaumont, Coachella Valley and Hemet. 

Those areas are dealing with wildfire smoke in addition to high ozone levels produced during the recent heat wave as heat and sunlight interact with local pollutants.

Jason Aldean cuts concert short after heat-related issues

Country star Jason Aldean said he was doing well after he cut short a concert because of the heat.

Aldean said a combination of dehydration and heat exhaustion forced him to cut off his show at Xfinity Theatre yesterday in Connecticut.

"Anybody at the show knows how hot it was," he said in a video posted to his Twitter account.

Aldean said he did receive intravenous fluids and plans to play tonight's show in Saratoga Springs, New York.

California’s Death Valley sizzles as brutal heat wave continues

Associated Press

Long the hottest place on Earth, Death Valley put a sizzling exclamation point today on a record warm summer that is baking nearly the entire globe by flirting with some of the hottest temperatures ever recorded, meteorologists said.

Temperatures in Death Valley, which runs along part of central California’s border with Nevada, were forecast to reach 128 degrees (53.33 degrees Celsius) today at the aptly named Furnace Creek, the National Weather Service said.

The hottest temperature ever record was 134 degrees in July 1913 at Furnace Creek, said Randy Ceverny, the records coordinator for the World Meteorological Organization, the body recognized as keeper of world records. Temperatures at or above 130 degrees have only been recorded on Earth a handful of times, mostly in Death Valley.

“With global warming, such temperatures are becoming more and more likely to occur,” Ceverny said in an email. “Long-term: Global warming is causing higher and more frequent temperature extremes. Short-term: This particular weekend is being driven by a very very strong upper level ridge of high pressure over the Western U.S.”

Meteorologists were tracking high clouds today in the area that could keep temperatures in check.

“The all-time record seems fairly safe today,” said Matt Woods, a meteorologist with the National Weather Service’s Las Vegas office, which monitors Death Valley.

Brush fires outside Los Angeles draw help from Utah and Colorado

Firefighters from Utah and Colorado are helping back up local efforts to contain fast-moving brush fires, Angeles National Forest said in a tweet.

"With the increasing fire activity, and extreme weather conditions, fire officials have staged additional firefighters from out of state," the forest said.

Fast-moving wildfires outside Los Angeles has already spurred evacuations.

Cloud cover brings slight respite in Phoenix, parts of Louisiana

The National Weather Service said Phoenix would probably not get record high temperatures thanks to cloud cover. It noted that temperatures would still be elevated.

The service also expanded its heat advisory for Louisiana, noting forecasts show heat index values reaching 105 to 110 degrees ahead of storms.

Boulder, Colo., National Weather Service issues heat advisory for Monday; near-record temperatures expected

NBC News

Near-record temperatures are expected in the Boulder, Colorado, region tomorrow.

NBC News

Over 1,000 U.S. flights canceled as severe storms take aim at the Northeast

Over 1,000 flights in and out of the Northeast have been canceled as storms have continued to batter the region over the weekend.

More than 1,160 flights into and out of the U.S. were canceled as of Sunday afternoon, over 350 of them going to and out of Newark Liberty International Airport in New Jersey, according to the online tracker FlightAware.

Severe weather prompted ground stops at John F. Kennedy and LaGuardia airports in New York and Newark Airport, according to the Federal Aviation Administration. Both airlines announced on Twitter that they’re experiencing flight disruptions due to weather and encouraged travelers to check with their airlines before heading to the airport.

Thunderstorms and heavy rain battered the Northeast over the weekend, with the heaviest rainfall expected to target New York, New Jersey, Pennsylvania, Delaware and Maryland.

Read the full story here.

Vermont faces another round of storms and possible flooding

Less than a week after intense storms generated heavy flooding, Vermont could again face another deluge.

NWS Burlington said this morning that a flood watch was in effect through the evening, with minor flooding expected.

Severe weather prompts ground stops at JFK and LaGuardia airports

NBC News

Inclement weather in the Northeast has led to flight suspensions and ground stops at JFK, LaGuardia and Newark airports, according to the FAA.

Northeast faces severe storms and tornado alerts

The National Weather Service issued a tornado watch for parts of Connecticut, Maine, Massachusetts, New Hampshire, New York and Rhode Island this morning through 3 p.m. ET.

Such warnings mean tornadoes could form. Tornado warnings are more serious and are meant to push people to take shelter immediately.

Storms are expected to batter the Northeast today, with the NWS forecasting a moderate risk of excessive rain and flooding for parts of the area.

Why the extended heat? Blame the heat dome.

persistent heat dome over the Southwest is bringing “anomalously hot summer weather” to much of the U.S. — and meteorologists have eyed aberrations in the jet stream as the culprit.

The jet stream, a ribbon of air that encircles the Northern Hemisphere at high altitudes, drives pressure changes that determine weather across North America. The jet stream’s wavy pattern creates areas of high and low pressure. 

In recent months, the jet stream’s patterns trapped and stalled a ridge of high pressure over northern Canada, which caused a heat wave and primed the landscape for the wildfires that later sent smoke pouring into the Midwest and the Eastern U.S. Another ridge of high pressure centered over Texas this month, sending temperatures soaring.

Phoenix faces another day of record heat

Phoenix faced another day of heat that could go down in the record books.

National Weather Service Phoenix tweeted this morning that record heat would continue across the region and through much of the coming week, with temperatures expected to remain above 114 through Thursday.

Number of fires in Canada 'well above average' for the time of year

Leila Sackur

The Tintagel wildfire in Tintagel, British Columbia. Handout / AFP - Getty Images

The number of fires is “well above average for this time of year” and well above the average for area burned at this time of year, according to the Canadian Wildland Fire Information System.

Describing the demand for firefighting resources as “extreme” on its website, the wildfire service said Canada had mobilized international resources to aid in its battle against record wildfires across the country.

It added that 406 of 548 new fires recorded since Wednesday had been attributed to lightning storms. British Columbia, Alberta and the Northwest Territories are the worst-affected, it said.

Severe weather affecting flights in Philadelphia

NBC News

9-month-old among missing as 3 dead, 4 others unaccounted for in Pennsylvania flash floods

Authorities are searching for four people, including an infant, after flash floods in Bucks County, Pennsylvania, killed three people yesterday.

A barrage of rain Saturday flooded Washington Crossing, where 11 vehicles were trapped, Upper Makefield Fire Chief Tim Brewer said today. A total of 6 to 7 inches of rain hit the area, which sits alongside the Delaware River, in less than an hour.

Ten people were rescued from their cars and the creek, but three adults were killed in the flooding, Brewer said. Four more people, including a 9-month-old and a 63-year-old, are unaccounted for.

Read the full story here.

Florida’s rising water temperatures raise concerns for health of coral reefs, scientists say


Rising temperatures in Florida’s waters due to climate change have created an extreme stressor for coral reefs, causing bleaching, which has scientists concerned.

Within the last week, as the South struggles under a heat wave, the National Oceanic and Atmospheric Administration has reported Florida water temperatures in the mid-90s. Normal water temperatures for this time of year should be 73 to 88 degrees, according to NOAA.

“In the last year, it’s been really depressing, because we’ve seen a lot of changes, and we’ve been monitoring sites from Miami for five years now, and we’re starting to see changes in those sites,” said Michael Studivan, a scientist with NOAA’s Coral Health and Monitoring Program.

The extreme heat has triggered coral bleaching, in which stressed corals expel their colorful algae symbionts, leaving them pale and vulnerable. Reefs are home to millions of species of marine life and are a boon to Florida's economy.

Excessive heat warning for Miami as temperatures could hit 112

The National Weather Service said today that Miami-Dade County will be under an excessive heat warning, as temperatures are expected to reach 112.

Much of the southern part of the state is already under heat advisories.

Drink fluids and stay indoors, meteorologists say

Leila Sackur

Warning of temperatures of 100 to 105 degrees, meteorologists in Texas said today that people should drink plenty of fluids.

“Stay in an air-conditioned room, stay out of the sun,” the National Weather Service office in Midland/Odessa said in a bulletin, in which it also urged people to “check up on relatives and neighbors.”

Advising people to “drink fluids,” it added that “children and pets should never be left unattended in vehicles under any circumstances.”

The mercury could hit 110 along sections of the Rio Grande, the bulletin said, adding that temperatures were also likely to hit triple digits in the Guadalupe and Delaware mountains, Chinati, the Marfa Plateau, Davis and the Chisos Basin, where the same advice holds.

Excessive rainfall and flash flooding possible in Northeast

Leila Sackur

Excessive rainfall and flash flooding are possible across the Northeast, along with the isolated threat of severe thunderstorms, the National Weather Service said in a bulletin Sunday.

More than 40 million people "are under moderate rick of excessive rainfall," the bulletin said, which brings "the potential for significant flash flooding."

In a separate tweet, the NWS office in Albany warned that portions of eastern and central New York could also experience flooding caused by heavy rainfall, while the office in Burlington warned that excessive runoff “may result in the flooding of rivers, creeks, streams, and other low-lying and flood-prone locations.”

Wildfires rage 'out of control' as another heat wave blisters Spain

Associated Press

The evacuated town of Tijarafe is surrounded by smoke billowing from a wildfire on the Spanish island of La Palma. Stringer / AFP - Getty Images

More than 2,000 people were evacuated as a wildfire raged “out of control” on La Palma in Spain’s Canary Islands yesterday, destroying around a dozen homes, authorities said.

La Palma is one of eight members of Spain’s Canary Islands archipelago off western Africa, just 60 miles from Morocco.

The blaze has affected an area of about 11,000 acres, and officials warned residents that the situation could worsen because a heat wave has made the terrain tinder dry.

The wildfire and evacuations come nearly two years after a three-month volcanic eruption caused devastation on La Palma, burying around 3,000 buildings, along with many banana plantations, roads and irrigation systems. Like large parts of Spain's drought-stricken mainland, the area has had below-average rainfall in recent years.

Triple-digit temperatures remain in Southwest

Leila Sackur

Daytime highs through interior California and the Great Basin will hit the century mark today and sit between 100 and 110 degrees, the National Weather Service said.

Parts of the high desert of Southern California, southern Nevada and southern Arizona will get temperatures as high as 115, it added.

Daytime temperatures in the Southwest and southern Floria and parts of the western Gulf Coast will also break record highs as well as daily minimums, providing little respite from daytime heat, the NWS said.

Canadian wildfire smoke returns to Northern U.S.

Leila Sackur

Smoke from wildfires tearing through the Canadian provinces of British Columbia and Alberta has reappeared in the U.S. and will continue to spread today, the National Weather Service warned.

Smoke has already crossed into Minnesota and the Dakotas and will enter skies above the Ohio Valley region by this afternoon, the NWS office in Wilmington, Ohio, tweeted.

The Sioux Falls weather service also said yesterday that air quality had reached “unhealthy levels” because of Canadian wildfire smoke, and it advised residents to reduce their physical activity and monitor for symptoms of coughing and chest pains.

Photo: Women escape the heat in a Los Angeles cooling tent

Damian Dovarganes / AP

What happens to the body during extreme heat?

Leila Sackur

Extreme temperatures make it difficult for the body to regulate its internal temperature control system, according to guidance issued by the Centers for Disease Control and Prevention.

In the heat, the body normally cools itself down by sweating. In extremely hot temperatures, sweating isn't always enough, according to the guidance published on the CDC's website. High body temperatures may damage the brain or other vital organs and could result in heatstroke, heat exhaustion, cramps and rashes, it adds.

When humidity is high, sweat will not evaporate as quickly, preventing the body from releasing heat quickly, according to the CDC.

Being very young or old or having underlying health conditions such as heart disease or poor circulation can also affect your body's ability to self-regulate, the CDC says.

Southern California firefighters battle 3 wildfires

Associated Press

Firefighters were battling three separate brush fires in blistering heat and low humidity in sparsely populated, hilly areas southeast of Los Angeles.

Nearly 1,000 homes were under evacuation orders, but there were no immediate reports of injuries or property loss, according to officials from the California Department of Forestry and Fire Protection, known as Cal Fire.

The fires were all within 40 miles of one another in Riverside County, where temperatures in some areas spiked into the triple digits.

“Heat is definitely a concern out there,” said April Newman of the Cal Fire/Riverside County Fire Department, adding that the blazes were burning through dense, dry brush in rugged terrain.

Heat poses 'serious risks,' to residents, Los Angeles mayor warns

Leila Sackur

The U.S. is in the midst of a summer of extremes

The word of the summer is “extreme.” 

Extreme flooding. Extreme heat. Extreme smoke.

Scientists have predicted a climate of extremes in report after report as the Earth warms because humans continue to belch fossil fuel pollution into the atmosphere. 

And now, it’s here — with a dizzying slew of broken records and heartbreaking scenes. 

Read the full story here.