Temperatures will reach 90 degrees Fahrenheit (32 Celsius) with high humidity this week from Chicago to New York and into southern Canada, increasing electricity demand and touching off heat warnings.
The thermometer is expected to climb to 97 today in New York and 90 every day through July 19. Chicago may reach 86 today and then advance into the 90s for the next four days. Boston and Washington will remain at about 90 through the work week and Toronto will reach that mark for at least the next four days.
From the Great Lakes to the U.S. Northeast and southern Quebec and Ontario, temperatures will be at least 8 degrees above normal through July 19, according to Commodity Weather Group LLC in Bethesda, Maryland.
“It’s going to be hot and humid,” said Rob Carolan, founder of Hometown Forecast Services Inc. in Nashua, New Hampshire. “It will last probably the entire work week and there is the potential that it will continue into Saturday.”
Electricity demand in New York is expected to peak between 4 p.m. and 5 p.m. at about 33,300 megawatts, said Ken Klapp, spokesman for the New York Independent System Operator, which runs the state’s power grid and wholesale-electricity market. The record was 33,939 megawatts set on Aug. 2, 2006.
Natural gas will be used to fuel about 32 percent of power plants this year, according to the Energy Information Administration.
Residents in New York City and adjoining Westchester County are being urged to conserve energy as temperatures soar, according to a statement from Consolidated Edison Inc. The New York-based company is also readying crews to deal with any potential outages.
Demand for electricity may be higher during this heat wave than earlier this month because it’s coming in the middle of a work week and will last a bit longer, said Matt Rogers, president of the Commodity Weather Group.
“Longer-term heat events build up higher intolerance and tends to build stronger demand over time,” Rogers said in an e-mail interview.
The soaring temperatures pose a health risk. From 1999 to 2009, heat killed an average of 658 people a year, according to the U.S. Centers for Disease Control and Prevention in Atlanta. People should avoid strenuous activity and drink plenty of water, according to the National Weather Service.
An excessive heat warning is in place for Philadelphia and Trenton, New Jersey, meaning the temperature will feel greater than 100, and heat advisories stretch from Pennsylvania to New Hampshire, including New York City and Boston, according to the weather service. Heat and humidity warnings have also been posted across southern Quebec by Environment Canada.
The temperature in Central Park reached 90 yesterday, according to the weather service. In Boston it was 93, 88 in Chicago and 89 in Washington.
A heat wave is defined as three consecutive days with temperatures of 90 or higher, according to the weather service.
High humidity will exacerbate the heat in the Northeast and Canada, according to Carolan.
Heat index values, how hot it feels, will be more than 100 degrees from Pennsylvania to New Hampshire because of the humidity, according to the weather service. Humid conditions will also grip Quebec, Carolan said.
“It’s pretty steamy stuff for them all the way up the St. Lawrence River,” Carolan said. “That is not something they are used to.”
Energy demand may also be sustained as the heat is expected to last because there won’t be as many late afternoon thunderstorms or clouds to take the edge off, Rogers said.
“That peak p.m. heat can last deeper into the evening hours and demand will not fall off as quickly as other events,” Rogers said in an e-mail interview. “The high humidity also slows the cooling process after the sun fades.”