Heat Wave To Hit Pacific Northwest, 'Dangerously Hot Conditions' Expected

The heat wave in the U.S. is forecast to intensify over the next few days, with afternoon temperatures in the Pacific Northwest expected to approach 110 degrees (Fahrenheit) in some parts of the interior region, the National Weather Service warned Tuesday.

Excessive Heat Warnings have been issued in several major metro areas across the country, including in New York City, Portland, Seattle, Philadelphia, St. Louis and Kansas City, with "dangerously hot conditions" expected in some parts, the NWS warned.

"Abnormally hot conditions" will remain across much of the U.S. mainland, including the Northeast, Mid-Atlantic and mid-section of the country, through mid-week, the NWS said.

Death Valley National Park in California.
A thermometer display showing a temperature of 130 degrees Fahrenheit (54 degrees Celsius) on June 17 at the Furnace Creek Visitor's Center at Death Valley National Park in California. The heat wave is expected to intensify in the Pacific Northwest, with temperatures approaching 110 degrees over the next few days. Patrick T. Fallon/AFP via Getty Images

The heat warnings are also in effect in other parts of New York State, Oregon, Washington, Missouri as well as in portions of New Jersey, Delaware and Idaho.

The warnings remain in place through to Saturday in most areas.

An Excessive Heat Warning is issued "when the combination of heat and humidity is expected to make it feel like it is 105 degrees or greater," the NWS explained.

Heat hazards in effect through Thu 8/12.

Excessive Heat Warning means Heat Index of 105+ is EXPECTED.

Excessive Heat Watch means Heat Index of 105+ is POSSIBLE.

Heat Advisory Means Heat Index of 95 to 99 for 2 consecutive days OR 100 to 104 for any length of time is EXPECTED. pic.twitter.com/5REvcorIwd

— NWS New York NY (@NWSNewYorkNY) August 10, 2021

"Daytime lows will be quite warm along the West Coast and east of the Mississippi River where numerous record warm minimum temperatures are possible on Wednesday and Thursday mornings. Looking further ahead, this heat wave is expected to peak during the second half of the week," the NWS said.

Heat Advisories are also in place in different pockets across the country, including northern California and in portions of Oregon, Washington, Texas, Arkansas, Louisiana, Mississippi, Illinois and Alabama, as well as in parts of the Northeast, including as far north as Maine and New Hampshire, according to the NWS.

An ice cream truck in Washington, D.C.
People waiting to buy ice cream from a street vendor in the Washington, D.C. area during a heat wave on June 30. Brendan Smialowski/AFP via Getty Images

A Heat Advisory is issued within 12 hours of the onset of "extremely dangerous heat conditions," the NWS said.

It means the "maximum heat index temperature is expected to be 100° [Fahrenheit] or higher for at least two days, and night time air temperatures will not drop below 75°," the NWS explained.

"However, these criteria vary across the country, especially for areas that are not used to dangerous heat conditions," the agency added.

Death Valley National Park in California.
Signage warning of extreme heat danger at the salt flats of Badwater Basin inside Death Valley National Park on June 17 in Inyo County, California. Patrick T. Fallon/AFP via Getty Images

In several areas where Excessive Heat Warnings and Heat Advisories are in place, "the excessive extreme heat will significantly increase the potential for heat related illnesses, particularly for those working or participating in outdoor activities," the NWS said.

Within the inland west side valley portions of Oregon, where an Excessive Heat Warning remains in place through 11 p.m. local time on Saturday, "extremely hot days, warm overnight lows, and the extended nature of this heat wave may make it especially difficult to get any relief from the heat," the NWS warned.

A sunset during 2021 California heat wave.
People watching a sunset as a child drinks from a water bottle on June 15 in Los Angeles, California amid a heat wave. Frederic J. Brown/AFP via Getty Images

Heat Wave Safety

The NWS advises the following precautions be taken amid the ongoing U.S. heat wave, as outlined at the agency's website:

  • Drink plenty of fluids and remain in an air-conditioned room. Keep out of the sun and check up on relatives and neighbors.
  • Never leave young children and pets unattended in vehicles under any circumstances.
  • Take extra precautions if you work outdoors or spend time outside. Where possible, strenuous activities should be rescheduled to take place in the early morning or evening hours.
  • Be aware of the signs and symptoms of heat exhaustion and heat stroke. See the NWS website for more information.
  • Wear lightweight and loose-fitting clothes where possible.
  • The Occupational Safety and Health Administration recommends taking frequent breaks in shaded or air-conditioned areas to reduce risk during outdoor work.
  • Those overcome by heat should be moved to a cool and shaded area. Heat stroke is an emergency. Call 911.

See the NWS website for more information about heat wave safety.

A man cooling off in Baltimore.
A man cooing off at a fountain in Baltimore, Maryland on June 30 during a heat wave. Jim Watson/AFP via Getty Images