(CNN) After searing heat suffocated large swaths of the US this weekend, the next few days are expected to bring more moderate temperatures to areas of the Northeast, while scorching weather in the Pacific Northwest will intensify.
Oppressive heat broke daily high temperature records Sunday in several northeastern cities -- prompting local officials to declare heat emergencies.
Newark Liberty International Airport hit a high of 102 degrees Fahrenheit, beating the previous record for July 24 set in 2010 of 99 degrees. In Boston, temperatures reached 100 degrees, topping the previous record of 98 degrees, which was set in 1933.
Providence, Rhode Island, hit 98 degrees, similarly besting a record of 94 set in 1933. And Philadelphia hit 99 degrees, just topping its record set in 2011 of 98 degrees.
More than 60 million people across the US are still under heat alerts Monday morning as high temperatures persist, primarily in the Northeast, central US and Pacific Northwest.
New York City, Newark and Boston remain under heat advisories until Monday evening, as heat index values could still climb into the upper 90s. Philadelphia is under an excessive heat warning until Monday evening, with heat index values anticipated to reach up to 100 degrees. But after Tuesday, temperatures in the Northeast will begin to drop closer to normal levels.
Meanwhile, parts of the Pacific Northwest -- which experienced a much cooler start to the year compared to eastern counterparts -- are under several excessive heat watches Monday that have the potential to be upgraded to heat warnings as the day goes on. Those high temperatures are expected to stretch on through the week and may continue into next week.
"Daytime highs will surpass the 90s each day and even eclipse the century mark in the Columbia River Gorge and Columbia River Basin," the Weather Prediction Center said. "Daily record highs will likely be broken from northern California to the Portland and Seattle metro areas on Tuesday."
A weekly outdoor foodtruck event, Riverfront Eats, in Spokane was canceled because of the extreme heat, according to a tweet from Riverfront Spokane.
Seattle is under a heat advisory from noon Tuesday through late Friday evening, and Portland is under an excessive heat warning starting Monday through Thursday evening with high temperatures between 98 and 103 degrees anticipated.
Seattle's Emergency Operations Center said in a news release Monday they would be opening cooling centers at community centers, libraries, senior centers and parks across the city.
And to prevent infrastructural damage, Seattle Department of Transportation personnel will spray cool water on the city's three major draw bridges to keep their movable parts from expanding and getting stuck, the release said.
In Oregon, Portland is under an excessive heat warning starting Monday until Thursday, and temperatures may reach as high as 100 degrees this week, according to the National Weather Service.
"The City of Portland is preparing to protect our most vulnerable residents during this approaching heat wave, and are working with our regional partners to ensure that there is a place for everyone at a cooling center," Portland Mayor Ted Wheeler said in a news release. "Start getting prepared now and don't forget to check on your neighbors."
Cities across the Central Plains -- including Dallas, Oklahoma City, Shreveport, Louisiana; Memphis, Tennessee; Little Rock, Arkansas; and Springfield, Missouri, also find themselves under heat advisories Monday, with high temperatures expected to climb into the upper 90s and triple digits through at least midweek.
Excessive heat warnings are in effect in Tulsa, Oklahoma, and Fort Smith, Arkansas, where heat index values could go as high as 112 degrees.
The weekend saw sizzling temperatures that put more than 90 million people under excessive heat alerts Sunday across the Northeast, Mid-Atlantic, Ohio River Valley, and Central Plains.
Cities baking under the prolonged heat moved to provide relief measures, including cooling stations, splash pads and additional outreach to people experiencing homelessness.
Concern for participants' safety pushed organizers of the New York City Triathlon to dramatically cut race distances and urge athletes to stay hydrated. Boston's annual triathlon event was postponed until next month due to the city's blistering heat.
Boston and Philadelphia extended their heat emergency warnings through Monday, warning residents to take measures to avoid heat-related illnesses as heat indexes -- a measure of how hot it actually feels due to combined heat and humidity -- are expected to be in the high 90s.
"As we lengthen the heat emergency for a second time, it is evident that a changing climate is a public health risk for our City," Boston Mayor Michelle Wu said in a statement. "I'm thankful for the many City employees who have helped us get through the first part of this emergency, and urge residents to continue to take care of one another."
Excessive heat poses real health hazards, particularly for high-risk groups like the elderly, children, and people with chronic illnesses and mental health problems, according to the CDC. When people's bodies are not able to cool down enough or lose too much water, they may be at risk of potentially life-threatening conditions such as heatstroke or heat exhaustion.
On Saturday, at least one person died from heat exposure in New York City, according to the medical examiner's office, which notes the man had preexisting conditions. The city's high temperature that day was 97 degrees.
Scorching heat left tens of thousands without power over the weekend as high temperatures drove outages, conditions which were exacerbated in some regions by ongoing storms.
In Boston's Dorchester neighborhood, approximately 20,000 customers were struck by a power outage Sunday, power company Eversource said in a statement.
Eversource was working to restore power to a remaining approximately 7,500 customers Sunday afternoon, and advised residents to avoid using large appliances during peak hours and adjust their thermostats to a few degrees higher than normal to reduce energy usage.
New York City electricity provider Con Edison said its workers continued "restoring scattered outages caused by the scorching heat" Sunday afternoon as the company also prepared for another weather challenge -- forecast thunderstorms Monday.
The company did not say how many of its customers were affected by the outages, but said in a statement Sunday that its employees have been "replacing and repairing cable and other equipment to get customers back in service."
The company said it planned to bring in additional employees to help fix damaged overhead wires and equipment in anticipation of Monday's storms.
Saturday afternoon storms in Greensburg, Pennsylvania, knocked out power for more than 10,000 customers, leaving impacted residents without electricity as near-record temperatures were forecast across the region.
Local power company West Penn Power said in a statement that high temperatures were impacting its services Sunday, even as it braced for additional storms. The company said on Twitter Sunday that it was working to restore service to around 6,000 customers without power, down from about 39,000 total customers impacted.