He would tuck three inside the waistband of his pants. A fourth he would sling in a plastic bag whose handles he would knot just under his chin, holding the icy cylinder against the back of his neck.

Even with that gear, Mr. Medina said he had quit early a few days this summer, heading home at 3 p.m. on the hottest days, instead of the usual 6. The heat, he said, “affects your whole nervous system, makes you grouchy; it makes you so you can’t stand your customers.”

At Natuzzi Brothers Ice Company in Queens, the phones ring nonstop once the temperature hits 90, Mr. Natuzzi said. This summer, he said, his company has been supplying dry ice to ice-cream stores to keep their products frozen, a request he said he rarely got last summer.

The shortage of orders during the cool early months of last summer led to significant losses, Mr. Natuzzi said, but this summer has been a different story. The company, whose warehouse holds 40 tons of ice, sold out its supply during the heat wave that started on the July 4 weekend. It has been running its delivery trucks up to 15 hours a day since then.

“It’s been quite a ride this summer,” Mr. Natuzzi said.

Exhausted as he is, it is not quite over. His company supplies ice to the food-service operations at the United States Open, which runs for two weeks. On the first day, the Open used about 20,000 pounds more than usual, he said. “I’ll look back and say that this is one summer I’ll never forget,” Mr. Natuzzi said.

At Con Edison, the summer of 2010 will be memorable for what did and did not happen. In the past three months, the utility’s customers drew more power off its grid than during any previous three-month period, according to data compiled by the company. But through successive heat waves, the electric distribution system held up, with only occasional localized disruptions.