PJM has issued a Maximum Generation Alert and Load Management Alert for June 23 as hot weather continues throughout the region PJM serves to ensure the reliable delivery of electricity to its customers across 13 states and the District of Columbia.
PJM issues a Maximum Generation Emergency Alert a day in advance of conditions that may require all generators to operate at their maximum output capability.
A dangerous heat wave moves from the Midwest toward the East Coast this week, and is expected to challenge long-standing heat records. In many places, temperatures could hit 100 degrees Fahrenheit and feel even warmer when humidity is factored in. “High overnight temperatures will create a lack of overnight cooling, significantly increasing the danger,” according tothe National Weather Service. Extreme heat warnings and advisories are in effect from Maine through the Carolinas, across the Ohio Valley and down into southern states like Mississippi and Louisiana. “It’s basically everywhere east of the Rockies,” National Weather Service meteorologist Mark Gehring told The Associated Press. “That is unusual, to have this massive area of high dew points and heat.”
Regional grid operator PJM Interconnection, which covers 13 states, issuedan energy emergency alert for today. The alert urges power transmission and generation owners to delay any planned maintenance so that no grid sources are out of commission as temperatures soar. A heat wave of this nature is rare this early in the summer. The last time temperatures hit 100 degrees in June in New York City, for example, was in 1995, according toAccuWeather. Heat waves are becoming more frequent and more intense as the climate warms. Below, graph shows how these events have been changing in recent decades.
Nighttime temperatures may remain in the mid-70s to low 80s in cities such as Baltimore, New York and Washington — limiting the body’s ability to cool down and increasing health risks.
“It’s very stressful on the body,” Mr. Hurley said. “You’re not able to cool down, especially if there’s no ventilation. If you don’t have cooling mechanisms at home, it’s hard to get that relief.”
Prolonged heat extremes pose a major public health threat because heat is the number-one weather-related killer in the U.S.; it causes more human deaths than hurricanes, tornadoes and floods combined. Heat can cause dehydration, which leads the blood to thicken and makes the heart pump harder. That organ and others can be damaged by too much exposure to heat.
The soaring, triple-digit high daily temperatures grab the headlines, and they definitely are a concern—but when temperatures only drop into the 80s and 90s at night, the body doesn’t get a chance to cool down. This is particularly a concern for those who lack air-conditioning, including unhoused populations. And heat is especially a health risk for the very young, the elderly and those with preexisting health conditions such as asthma and heart disease.
Overnight lows in the U.S. are rising twice as fast as daytime highs, according to Climate Central, a nonprofit research and news organization. A 2022 Climate Central analysis found that overnight lows in the U.S. have risen by 2.5 degrees F on average since 1970. In Phoenix they have risen by 5.7 degrees F over that same period.
Jeff Goodell’s The Heat Will Kill You First (2023) does a good job of describing the physiological problems associated with overheating.
Humans cool off via two mechanisms, evaporative cooling (sweat evaporation is heat-consuming process) and direct heat transfer (cool air, cool surfaces, cool drink).
Yeah – I walked seven miles in Chicago on Saturday – clear sky, mid-nineties temperature, heat index 103°F, and I wouldn’t have even tried that if it weren’t for the fact that it was very windy (plus, stopping one place for a bottle of iced tea, another place for a bottle of apple juice). Very mindful of what my body was telling me, walked more slowly than usual, and ten minutes in a cool shower once I got home. But after dark, sitting on the balcony with the strong breeze was great, though the city broke it’s record for warmest overnight low for June 21, by four degrees. The prior record was from 1923.
Yesterday? I stayed in.