More than 600 crews were working to address the Sunday...

More than 600 crews were working to address the Sunday night outages, a PSEG LI spokeswoman said. Credit: Newsday / John Paraskevas

Sunday was hot. Really hot. But somehow not quite record-setting. 

Even as it felt like 109 degrees outside, Sunday's high temperature was only 99 degrees, cooler than both the record for the same day and the hottest day ever recorded in Islip, according to the National Weather Service. 

On the same day in 1991, the mercury hit 101 at Long Island MacArthur Airport. That was still below the record, set on July 3, 1966, for highest temperature ever recorded at the airport: 104. 

Sunday was not even the most sweltering day of the weekend. While it beat Saturday's high temperature of 97 — which matched 1991's record for hottest July 20 — it still felt a smidgen cooler than Saturday's heat index of 111.   

The heat will break in a big way Monday with a 60 percent chance of showers and thunderstorms throughout the day and into the night. The high Monday is expected to hit 82 with a low of 69, forecasters said, with a tenth to a quarter of an inch possible.

The coming cool down can’t come fast enough for thousands who lost power Sunday on Long Island because of the heat.

At the height of the outages, nearly 6,000 customers did not have electricity around 7:30 p.m. Sunday, according to PSEG Long Island. That figure dropped to about 3,500 customers around 8:15 p.m. By Monday morning, just about 200 customers remained without power, according to the PSEG outage map.

More than 600 crews were working to address the outages Sunday night, PSEG LI spokeswoman Elizabeth Flagler said, adding "we've been able to stay right on top of outages as they come in," Flagler said, adding there is "hardly any backlog."

The National Weather Service expected to keep an excessive heat warning in effect through 9 p.m.

The weather service warned that the extreme heat can quickly cause heat exhaustion or heat stroke among the at-risk population who can’t stay cool.

Symptoms of heat exhaustion may include cool, moist skin with goose bumps when in the heat, heavy sweating, faintness, dizziness, fatigue, weak, rapid pulse, low blood pressure upon standing, muscle cramps, nausea and headache, according to the Mayo Clinic.

Heat stroke, however, is more serious than heat exhaustion, and symptoms may include high body temperature, confusion, slurred speech, irritability, delirium, seizures and coma, alteration in sweating, nausea and vomiting, flushed skin, rapid breathing, racing heart rate and a headache, according to the Mayo Clinic.

Hospitals were seeing an increase in heat-related patients over the weekend, according to Catholic Health Services of Long Island.

“We treated an increased number of patients with heat-related complaints yesterday [syncope, fatigue, dehydration],”  said Dr. Christopher Raio, the Rockville Centre-based agency's chairman of emergency medicine. “Some doing work outside, some actually from the beach, and a few elderly with no AC at home. We expect the same today.”

Stony Brook University Hospital had one heat-related emergency department visit Saturday, spokeswoman Kali Chan said.

Northwell spokeswoman Diane O'Donnell said on Sunday, "So far we have had 30 patients come to our Long Island EDs yesterday from heat-related complaints with eight admitted."

While the temperature soared into the high-90s, even the low temperatures were high.

According to the National Weather Service, Saturday night’s low of 78 degrees was a record high temperature tied with the record for that date set on July 20, 2013. A weather service spokesman said that temperature has been tied a few times since 2013.

George Gorman, the regional director for Long Island for the state Office of Parks, Recreation and Historic Preservation, said state parks and beaches were crowded Saturday but didn't reach capacity and he expected the same for Sunday. A spokeswoman for Nassau County also said its beaches were not at capacity.

With Rachelle Blidner

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